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1

Toxicity of haloacetic acids to freshwater algae  

Microsoft Academic Search

Haloacetic acids (HAA), such as trichloroacetic acid (TCA), are commonly occurring by-products from disinfection and bleaching processes using sodium hypochlorite. Currently, the lowest no observed effect concentration (NOEC) for TCA is reported to be 8.7?gL?1, which was derived from a toxicity study conducted in 1981 on Chlorella pyrenoidosa. The purity of the test material was not documented and it is

Jayne F. Roberts; Roger van Egmond; Oliver R. Price

2010-01-01

2

Mammalian cell cytotoxicity and genotoxicity of the haloacetic acids, a major class of drinking water disinfection by-products.  

PubMed

The haloacetic acids (HAAs) are disinfection by-products (DBPs) that are formed during the disinfection of drinking water, wastewaters and recreational pool waters. Currently, five HAAs [bromoacetic acid (BAA), dibromoacetic acid (DBAA), chloroacetic acid (CAA), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA); designated as HAA5] are regulated by the U.S. EPA, at a maximum contaminant level of 60 ?g/L for the sum of BAA, DBAA, CAA, DCAA, and TCAA. We present a comparative systematic analysis of chronic cytotoxicity and acute genomic DNA damaging capacity of 12 individual HAAs in mammalian cells. In addition to the HAA5, we analyzed iodoacetic acid (IAA), diiodoacetic acid (DiAA), bromoiodoacetic acid (BIAA), tribromoacetic acid (TBAA), chlorodibromoacetic acid (CDBAA), bromodichloroacetic acid (BDCAA), and bromochloroacetic acid (BCAA). Their rank order of chronic cytotoxicity in Chinese hamster ovary cells was IAA > BAA > TBAA > CDBAA > DIAA > DBAA > BDCAA > BCAA > CAA > BIAA > TCAA > DCAA. The rank order for genotoxicity was IAA > BAA > CAA > DBAA > DIAA > TBAA > BCAA > BIAA > CDBAA. DCAA, TCAA, and BDCAA were not genotoxic. The trend for both cytotoxicity and genotoxicity is iodinated HAAs > brominated HAAs > chlorinated HAAs. The use of alternative disinfectants other than chlorine generates new DBPs and alters their distribution. Systematic, comparative, in vitro toxicological data provides the water supply community with information to consider when employing alternatives to chlorine disinfection. In addition, these data aid in prioritizing DBPs and their related compounds for future in vivo toxicological studies and risk assessment. PMID:20839218

Plewa, Michael J; Simmons, Jane Ellen; Richardson, Susan D; Wagner, Elizabeth D

2010-01-01

3

Haloacetic acids in the aquatic environment. Part I: macrophyte toxicity  

Microsoft Academic Search

Haloacetic acids (HAAs) are contaminants of aquatic ecosystems with numerous sources, both anthropogenic and natural. The toxicity of HAAs to aquatic plants is generally uncharacterized. Laboratory tests were conducted with three macrophytes (Lemna gibba, Myriophyllum sibiricum and Myriophyllum spicatum) to assess the toxicity of five HAAs. Myriophyllum spp. has been proposed as required test species for pesticide registration in North

Mark L Hanson; Keith R Solomon

2004-01-01

4

A study of the partitioning of haloacetates into cetylpyridinium chloride micelles using semiequilibrium dialysis and ultrafiltration.  

PubMed

Haloacetic acids, formed in drinking water during disinfection by chlorination, pose significant risks to human health. Semiequilibrium dialysis and ultrafiltration experiments were used to examine the partitioning of the five regulated haloacetic acids (HAA(5)) viz. chloro-, dichloro-, trichloro-, bromo-, and dibromoacetic acids into cetylpyridinium chloride (CPC) micelles across a range of micellar mole fraction, surfactant concentration, and added NaCl conditions. The results of these experiments were successfully correlated using a nonlinear three-site equilibrium model, which combines thermodynamic relations with the Oosawa two-state binding theory, incorporates allowances for nonideality, and includes a parameter to account for haloacetate solubilization. Micellar-enhanced ultrafiltration using CPC provided excellent HAA(5) removal efficiencies of over 98%. PMID:23313349

Roach, Jim D; Premjee, Mohammed M; Buddhavarapu, Sivacharan; Hassib, Ahmed

2013-03-15

5

Sources and haloacetic acid/trihalomethane formation potentials of aquatic humic substances in the Wakarusa River and Clinton Lake near Lawrence, Kansas  

USGS Publications Warehouse

Gram quantities of aquatic humic substances (AHS) were extracted from the Wakarusa River-Clinton Lake Reservoir system, near Lawrence, KS, to support nuclear magnetic resonance (NMR) experimental studies, report concentrations of dissolved organic carbon (DOC) and AHS, define sources of the AHS, and determine if the AHS yield sufficient quantities of haloacetic acids (HAA5) and trihalomethanes (THM4) that exceed U.S. Environmental Protection Agency (EPA) Maximum Contaminant Levels (MCL) in drinking water. AHS from the Wakarusa River and Clinton Lake originated from riparian forest vegetation, reflected respective effects of soil organic matter and aquatic algal/bacterial sources, and bore evidence of biological degradation and photodegradation. AHS from the Wakarusa River showed the effect of terrestrial sources, whereas Clinton Lake humicacid also reflected aquatic algal/bacterial sources. Greater amounts of carbon attributable to tannin-derived chemical structures may correspond with higher HAA5 and THM4 yields for Clinton Lake fulvic acid. Prior to appreciable leaf-fall from deciduous trees, the combined (humic and fulvic acid) THM4 formation potentials for the Wakarusa River approached the proposed EPA THM4 Stage I MCL of 80 ??g/L, and the combined THM4 formation potential for Clinton Lake slightly exceeded the proposed THM4 Stage II MCL of 40 ??g/L. Finally, AHS from Clinton Lake could account for most (>70%) of the THM4 concentrations in finished water from the Clinton Lake Water Treatment Plant based on September 23, 1996, THM4 results.Gram quantities of aquatic humic substances (AHS) were extracted from the Wakarusa River-Clinton Lake Reservoir system, near Lawrence, KS, to support nuclear magnetic resonance (NMR) experimental studies, report concentrations of dissolved organic carbon (DOC) and AHS, define sources of the AHS, and determine if the AHS yield sufficient quantities of haloacetic acids (HAA5) and trihalomethanes (THM4) that exceed U.S. Environmental Protection Agency (EPA) Maximum Contaminant Levels (MCL) in drinking water. AHS from the Wakarusa River and Clinton Lake originated from riparian forest vegetation, reflected respective effects of soil organic matter and aquatic algal/bacterial sources, and bore evidence of biological degradation and photodegradation. AHS from the Wakarusa River showed the effect of terrestrial sources, whereas Clinton Lake humic acid also reflected aquatic algal/bacterial sources. Greater amounts of carbon attributable to tannin-derived chemical structures may correspond with higher HAA5 and THM4 yields for Clinton Lake fulvic acid. Prior to appreciable leaf-fall from deciduous trees, the combined (humic and fulvic acid) THM4 formation potentials for the Wakarusa River approached the proposed EPA THM4 Stage I MCL of 80 ??g/L, and the combined THM4 formation potential for Clinton Lake slightly exceeded the proposed THM4 Stage II MCL of 40 ??g/L. Finally, AHS from Clinton Lake could account for most (>70%) of the THM4 concentrations in finished water from the Clinton Lake Water Treatment Plant based on September 23, 1996, THM4 results.Gram quantities of aquatic humic substances were extracted from the Wakarusa River-Clinton Lake Reservoir system near Lawrence, KS, and concentrations of dissolved organic carbon (DOC) and the proportions of DOC accountable as aquatic humic substances were determined. In addition, the sources of the aquatic humic substances were defined, and the haloacetic acids/trihalomethanes formation potentials were assessed. The samples were collected over the period September 10-October 10, before any appreciable leaf-fall occurred from deciduous trees. Results showed that the humic substances produced considerable yields of haloacetic acids and trihalomethanes, with higher yields noted for fulvic acid from Clinton Lake. The aquatic humic substances were derived from sources outside and within the Wakarusa River and Clinton Lake and could yield sufficient trih

Pomes, M.L.; Larive, C.K.; Thurman, E.M.; Green, W.R.; Orem, W.H.; Rostad, C.E.; Coplen, T.B.; Cutak, B.J.; Dixon, A.M.

2000-01-01

6

Haloacetic acids in the aquatic environment. Part I: macrophyte toxicity.  

PubMed

Haloacetic acids (HAAs) are contaminants of aquatic ecosystems with numerous sources, both anthropogenic and natural. The toxicity of HAAs to aquatic plants is generally uncharacterized. Laboratory tests were conducted with three macrophytes (Lemna gibba, Myriophyllum sibiricum and Myriophyllum spicatum) to assess the toxicity of five HAAs. Myriophyllum spp. has been proposed as required test species for pesticide registration in North America, but few studies have been conducted under standard test conditions. The HAAs in the present experiments were monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA). MCA was the most toxic to Myriophyllum spp. with EC50 values ranging from 8 to 12.4 mg/l depending on the endpoint, followed by DCA (EC50 range 62-722.5 mg/l), TCA (EC50 range 49.5-1702.6 mg/l), CDFA (EC50 range 105.3 to >10,000 mg/l) and with TFA (EC50 range 222.1 to 10,000 mg/l) the least toxic. Generally, L. gibba was less sensitive to HAA toxicity than Myriophyllum spp., with the difference in toxicity between them approximately threefold. The range of toxicity within Myriophyllum spp. was normally less than twofold. Statistically, plant length and node number were the most sensitive endpoints as they had the lowest observed coefficients of variation, but they were not the most sensitive to HAA toxicity. Toxicological sensitivity of endpoints varied depending on the measure of effect chosen and the HAA, with morphological endpoints usually an order of magnitude more sensitive than pigments for all plant species. Overall, mass and root measures tended to be the most sensitive indicators of HAA toxicity. The data from this paper were subsequently used in an ecological risk assessment for HAAs and aquatic plants. The assessment found HAAs to be of low risk to aquatic macrophytes and the results are described in the second manuscript of this series. PMID:15182970

Hanson, Mark L; Solomon, Keith R

2004-08-01

7

MICROEXTRACTION OF NINE HALOACETIC ACIDS IN DRINKING WATER AT MICROGRAM PER LITER LEVELS WITH ELECTROSPRAY-MASS SPECTROMETRY OF STABLE ASSOCIATION COMPLEXES  

EPA Science Inventory

Haloacetic acids are disinfection by-products of the chlorination of drinking water. This paper presents the analysis of all nine chloro- and bromo-haloacetic acids (HAA9) at sub- ug L-1 by microextraction with detection by electrospray mass spectrometry. The haloacetic acids are...

8

BROMOCHLORO-HALOACETIC ACIDS: EFFECTS ON MOUSE EMBRYOS IN VITRO AND QSAR CONSIDERATIONS  

EPA Science Inventory

The haloacetic acids (HAA) are a family of chemicals that are drinking water disinfection byproducts. We previously reported that bromo- and chloro-acetic acids altered embryonic development when mouse conceptuses were directly exposed to these xenobiotics in whole embryo culture...

9

Determination of haloacetic acids in human urine by headspace gas chromatography–mass spectrometry  

Microsoft Academic Search

Haloacetic acids (HAAs) are water disinfection byproducts (DBPs) formed by the reaction of chlorine oxidizing compounds with natural organic matter in water containing bromine. HAAs are second to trihalomethanes as the most commonly detected DBPs in surface drinking water and swimming pools. After oral exposure (drinking, showering, bathing and swimming), HAAs are rapidly absorbed from the gastrointestinal tract and excreted

M. J. Cardador; M. Gallego

2010-01-01

10

ENANTIOMERIC COMPOSITION OF CHIRAL HALOACETIC ACID AND HALOACETONITRILE DISINFECTION BYPRODUCTS IN DRINKING WATER  

EPA Science Inventory

Haloacetic acids and haloacetonitriles are well-known chlorine disinfection byproducts (DBPs), formed by the reaction of chlorine with natural organic matter. These compounds are of concern to public health because of their possible toxicological properties. Studies to date on th...

11

Haloacetic acids in the aquatic environment. Part II: ecological risk assessment  

Microsoft Academic Search

Haloacetic acids (HAAs) are environmental contaminants found in aquatic ecosystems throughout the world as a result of both anthropogenic and natural production. The ecological risk posed by these compounds to organisms in freshwater environments, with a specific focus on aquatic macrophytes, was characterized. The plants evaluated were Lemna gibba, Myriophyllum spicatum and M. sibiricum and the HAAs screened were monochloroacetic

Mark L Hanson; Keith R Solomon

2004-01-01

12

Improving methodological aspects of the analysis of five regulated haloacetic acids in water samples by solid-phase extraction, ion-pair liquid chromatography and electrospray tandem mass spectrometry.  

PubMed

Haloacetic acids (HAAs) are organic pollutants originated from the drinking water disinfection process, which ought to be controlled and minimized. In this work a method for monitoring haloacetic acids (HAAs) in water samples is proposed, which can be used in quality control laboratories using the techniques most frequently available. Among its main advantages we may highlight its automated character, including minimal steps of sample preparation, and above all, its improved selectivity and sensitivity in the analysis of real samples. Five haloacetic acids (HAA5) were analyzed using solid-phase extraction (SPE) combined with ion-pair liquid chromatography and tandem mass spectrometry. For the optimization of the chromatographic separation, two amines (triethylamine, TEA and dibutylamine, DBA) as ion pair reagents were compared, and a better selectivity and sensitivity was obtained using DBA, especially for monohaloacetic acids. SPE conditions were optimized using different polymeric adsorbents. The electrospray source parameters were studied for maximum precursor ion accumulation, while the collision cell energy of the triple quadrupole mass spectrometer was adjusted for optimum fragmentation. Precursor ions detected were deprotonated, dimeric and decarboxylated ions. The major product ions formed were: ionized halogen atom (chloride and bromide) and decarboxylated ions. After enrichment of the HAAs in Lichrolut EN adsorbent, the limits of detection obtained by LC-MS/MS analysis (between 0.04 and 0.3 ng mL(-1)) were comparable to those obtained by GC-MS after derivatization. Linearity with good correlation coefficients was obtained over two orders of magnitude irrespective of the compound. Adequate recoveries were achieved (60-102%), and the repeatability and intermediate precision were in the range of 2.4-6.6% and 3.8-14.8%, respectively. In order to demonstrate the usefulness of the method for routine HAAs monitoring, different types of water samples were analyzed. In swimming pool water samples the ?HAAs were determined between 76 and 154 ng mL(-1). PMID:22608419

Prieto-Blanco, M C; Alpendurada, M F; López-Mahía, P; Muniategui-Lorenzo, S; Prada-Rodríguez, D; Machado, S; Gonçalves, C

2012-05-30

13

The solvent effect on the acidities of haloacetic acids in aqueous solution. A RISM-SCF study  

NASA Astrophysics Data System (ADS)

The acidities of acetic, fluoracetic and chloroacetic acids in aqueous solution are calculated by means of the ab initio method combined with the reference interaction site method in the statistical mechanics of molecular liquids (the RISM-SCF method). The inversion in the order of acidities experimentally observed when a series of haloacetic acids is immersed into aqueous solution is reproduced. It is shown that the inversion is caused by competition between substitution and solvation effects. The solvation effect is discussed in molecular detail in terms of the charge distribution of the solute and the solute-solvent radial distribution functions.

Kawata, Masaaki; Ten-no, Seiichiro; Kato, Shigeki; Hirata, Fumio

1995-06-01

14

Relationship between nine haloacetic acids with total organic halogens in different experimental conditions.  

PubMed

The effects of pH and bromide ion concentration on the formation of nine haloacetic acids (HAAs) and total organic halogens (TOX) in chlorinated drinking water have been evaluated. In an extensive study, the relationships of nine HAAs with TOX have been investigated. Honesty Significant Differences test (HSD) and ANOVA tests were used for the statistical analyses. The study determined the concentration range of nine HAAs as of a percentage of TOX at varying experimental conditions. Statistical analyses showed that the parameters pH and Br had significant effects on the formation of nine HAAs and TOX. This study also showed that brominated and mixed species of HAAs would be dominant in the presence of high bromide ion concentration which contributes a high percentage of the TOX. The results of this study could be used to set up a maximum contaminant level of TOX as a water quality standard for chlorination by-products. PMID:23551829

Pourmoghadas, Hossein; Kinman, Riley N

2013-01-01

15

Haloacetic acids in the aquatic environment. Part II: ecological risk assessment.  

PubMed

Haloacetic acids (HAAs) are environmental contaminants found in aquatic ecosystems throughout the world as a result of both anthropogenic and natural production. The ecological risk posed by these compounds to organisms in freshwater environments, with a specific focus on aquatic macrophytes, was characterized. The plants evaluated were Lemna gibba, Myriophyllum spicatum and M. sibiricum and the HAAs screened were monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA). Laboratory toxicity data formed the basis of the risk assessment, but field studies were also utilized. The estimated risk was calculated using hazard quotients (HQ), as well as effect measure distributions (EMD) in a modified probabilistic ecological risk assessment. EMDs were used to estimate HAA thresholds of toxicity for use in HQ assessments. This threshold was found to be a more sensitive measure of low toxicity than the no observed effect concentrations (NOEC) or the effective concentration (EC10). Using both deterministic and probabilistic methods, it was found that HAAs do not pose a significant risk to freshwater macrophytes at current environmental concentrations in Canada, Europe or Africa for both single compound and mixture exposures. Still, HAAs are generally found as mixtures and their potential interactions are not fully understood, rendering this phase of the assessment uncertain and justifying further effects characterization. TCA in some environments poses a slight risk to phytoplankton and future concentrations of TFA and CDFA are likely to increase due to their recalcitrant nature, warranting continued environmental surveillance of HAAs. PMID:15182971

Hanson, Mark L; Solomon, Keith R

2004-08-01

16

Insight into changes during coagulation in NOM reactivity for trihalomethanes and haloacetic acids formation.  

PubMed

Natural organic matter (NOM) in raw water can contribute in many ways to the poor quality of drinking water, including the formation of disinfection byproducts such as trihalomethanes (THM) and haloacetic acids (HAA) during disinfection. This paper investigates the role of individual NOM fractions on changes in THM and HAA formation during coagulation with iron chloride (FeCl3) and a combination of polyaluminium chloride and iron chloride (FeCl3/PACl). The dissolved organic carbon (DOC) in the raw water and after coagulation was fractionated into four fractions, based on their hydrophobicity. Fractionation showed that most of the DOC (68%) in the raw water comes from the fulvic acid fraction, yielding 41% of the total THM precursors and 21% of the total HAA precursors. Both coagulants remove the humic acid fraction, but result in different changes to the reactivity of the remaining NOM fractions towards THM and HAA formation, indicating that coagulation occurs by different pathways, depending upon the type of coagulant used. In particular, significant changes in the reactivities of the hydrophilic acidic and non-acidic fractions were observed. PMID:23428464

Tubi?, Aleksandra; Agbaba, Jasmina; Dalmacija, Božo; Molnar, Jelena; Maleti?, Snežana; Watson, Malcolm; Perovi?, Svetlana Ugar?ina

2013-03-30

17

Distribution of haloacetic acids in the water columns of the Laurentian Great Lakes and Lake Malawi.  

PubMed

Haloacetic acids (HAAs) are persistent and mildly phytotoxic compounds that have been detected in many aquatic environments, including the waters of the Great Lakes. Sources of HAAs, especially of trifluoroacetic acid (TFA), are not well understood. In this study we assessed the influence of urbanization on the concentrations and profiles of HAAs in the Laurentian Great Lakes and in Lake Malawi, an African Great Lake. Vertical depth profiles for these compounds were taken for each of the Great Lakes with additional profiles taken 2 years later for Lakes Erie and Ontario. The results showed that while TFA was relatively constant throughout the water column, the chloroacetic acids (CAAs) varied with depth. There was a trend of increasing TFA proceeding from Lake Superior to Lake Ontario (18-150 ng/L). Total CAA concentrations were relatively constant throughout the lakes (approximately 500 ng/L) with dichloroacetic acid being the most abundant. No bromoacetic acids were detected. In the Detroit River, a connecting channel between Lakes Huron and Erie, the TFA values were similar to those in Lake Huron, but the CAAs levels were higher than in the upstream lakes and dependent on location, indicating inputs from urban areas along the river. These results were compared to those from Lake Malawi, which has a high population density within the watershed but no heavy industry. CAAs were nondetectable, and TFA concentrations were just at the detection limit (1 ng/L). Total HAA in the water column of Lakes Superior and Huron was compared to annual precipitation inputs at a site situated near both lakes. For Lake Huron, precipitation was a minor contributor to the total HAA inventory of the lake, but for Lake Superior precipitation could be the major contributor to the mass of HAA in this lake. Generally, high HAA levels paralleled the degree of industrial activity in the adjacent waters. PMID:12026968

Scott, Brian F; Spencer, Christine; Marvin, Christopher H; MacTavish, David C; Muir, Derek C G

2002-05-01

18

Effect of the chlorinated washing of minimally processed vegetables on the generation of haloacetic acids.  

PubMed

Chlorine solutions are usually used to sanitize fruit and vegetables in the fresh-cut industry due to their efficacy, low cost, and simple use. However, disinfection byproducts such as haloacetic acids (HAAs) can be formed during this process, which can remain on minimally processed vegetables (MPVs). These compounds are toxic and/or carcinogenic and have been associated with human health risks; therefore, the U.S. Environmental Protection Agency has set a maximum contaminant level for five HAAs at 60 ?g/L in drinking water. This paper describes the first method to determine the nine HAAs that can be present in MPV samples, with static headspace coupled with gas chromatography-mass spectrometry where the leaching and derivatization of the HAAs are carried out in a single step. The proposed method is sensitive, with limits of detection between 0.1 and 2.4 ?g/kg and an average relative standard deviation of ?8%. From the samples analyzed, we can conclude that about 23% of them contain at least two HAAs (<0.4-24 ?g/kg), which showed that these compounds are formed during washing and then remain on the final product. PMID:22747435

Cardador, Maria Jose; Gallego, Mercedes

2012-07-25

19

A fully-automated analyzer for determining haloacetic acid concentrations in drinking water.  

PubMed

A fully-automated, on-line, real-time analyzer has been developed for preconcentration and analysis of haloacetic acids (HAAs). Preconcentration of HAAs is achieved by sample acidification and solid phase extraction onto a hydrophobic polymeric resin using sequential injection analysis (SIA). The HAAs preconcentrate is then analyzed using post-column reaction-ion chromatography (PCR-IC), which is selective for HAAs. Systematic optimization of SIA preconcentration parameters are described followed by detailed method detection limit (MDL), accuracy, precision, and linearity studies. MDL values for the individual HAA9 species range from 0.4 to 0.9?gL(-1). Side-by-side comparison studies of HAAs analysis in 14 real-world drinking water samples from Alabama, Arkansas, Kentucky, Minnesota, Missouri, Mississippi, New York, Pennsylvania and Tennessee are presented that compare the optimized SIA-PCR-IC to USEPA Method 552.3. Trace levels of HAAs detected in select samples are reported, and the bias values calculated between the two methods are typically less than 5?gL(-1) for eight of the nine individual HAAs. PMID:25303464

Henson, Christina M; Emmert, Gary L; Simone, Paul S

2014-12-01

20

Comparison of haloacetic acids in the environment of the Northern and Southern Hemispheres.  

PubMed

Haloacetic acids (HAAs) are a family of compounds whose environmental concentrations have been extensively studied, primarily in Europe. Depending on the compound, their sources are believed to be both natural and anthropogenic. To better understand possible sources and contribute to the knowledge of the global distribution of these compounds, especially between the Northern and Southern Hemispheres, samples of precipitation, soils, and conifer needles were collected from Canada, Malawi, Chile, and the U.K. Precipitation samples exhibited highest HAA concentrations in collections from Canada, and lowest in those from Malawi. Malawi samples contained measurable levels of monobromoacetic acid (MBA) (56 ng/ L) unlike those from most other locations (< 9 ng/L). Soil HAA concentration levels were highest in the U.K. (e.g., 7.3 ng/g average TCA) and lowest in Malawi (0.8 ng/g average TCA), with Chile having higher levels (4.8 ng/g average TCA) than Canada (3 ng/g average TCA). Malawi soils contained small amounts of MBA (2 ng/g), in common with the two most southern of the 11 Chilean sites. Analysis of soil cores (10-cm depth sliced at 1 cm) from sites in Malawi and Chile showed that trichloroacetic acid (TCA) generally declined with depth while mono- and dichloroacetic acid (MCA and DCA) showed no trend. MCA, DCA, and TCA concentrations in archived U.K. soil samples increased by factors of 2, 4, and 5-fold over 75 years while TFA showed no consistent trend. Monochloroacetic acid (MCA) was detected in pine needles collected from Malawi. U.K. needle samples had the highest concentrations of all chloroacetic acids (CAAs): MCA, 2-18 ng/g; dichloroacetic acid (DCA), 2-38 ng/g; and trichloroacetic acid (TCA), 28-190 ng/g. Conifer needles from Canada and Chile contained CAAs at levels ranging from < 2 to 16 ng/g wet wt. Trifluoroacetic acid concentrations generally declined with increasing elevation in the samples from the Rocky Mountains in western Canada. The results indicate that concentrations of HAAs are greatest in the industrialized Northern Hemisphere but there are significant amounts of these compounds in the less industrialized Southern Hemisphere. PMID:16323760

Scott, B F; Spencer, C; Martin, J W; Barra, R; Bootsma, H A; Jones, K C; Johnston, A E; Muir, D C G

2005-11-15

21

Formation of haloacetic acids from dissolved organic matter fractions during chloramination.  

PubMed

The objective of this study was to investigate the roles of dissolved organic matter (DOM) fractions, pH and bromide concentration in the formation of haloacetic acids (HAA) during chloramination. DOM from two surface waters with a low (2.9 L/mg-m) and high (5.1 L/mg-m) specific UV absorbance (SUVA(254)) values was isolated and fractionated into three fractions based on the hydrophobicity [i.e., hydrophobic (HPO), transphilic (TPH) and hydrophilic (HPI)]. DOM mass balances and DBP reactivity checks were performed to characterize the effects of isolation and fractionation steps. The fractions were chloraminated at three pHs and three bromide concentrations. The results showed that pH was the most important factor controlling HAA formation and speciation. The HAA yields significantly decreased with increase in pH from 6.3 to 9.0. The impact of bromide in the formation of brominated HAA species also became less important with increasing pH, and no brominated specie was detectable at pH 9. HPO fractions of the two source waters consistently showed higher HAA yields than TPH and HPI fractions. On the other hand, HPI fractions showed higher bromine incorporation than HPO and TPH fractions. To maintain higher and relatively stable combined chlorine residuals while reducing HAA formation, water utilities may consider keeping pH above 7.5 as one strategy. This will also lower the formation of brominated HAA species which have been shown to be more cyto- and geno-toxic than their chlorinated analogs. PMID:23245540

Hong, Ying; Song, Hocheol; Karanfil, Tanju

2013-03-01

22

Method of analysis at the U.S. Geological Survey California Water Science Center, Sacramento Laboratory - determination of haloacetic acid formation potential, method validation, and quality-control practices  

USGS Publications Warehouse

An analytical method for the determination of haloacetic acid formation potential of water samples has been developed by the U.S. Geological Survey California Water Science Center Sacramento Laboratory. The haloacetic acid formation potential is measured by dosing water samples with chlorine under specified conditions of pH, temperature, incubation time, darkness, and residual-free chlorine. The haloacetic acids formed are bromochloroacetic acid, bromodichloroacetic acid, dibromochloroacetic acid, dibromoacetic acid, dichloroacetic acid, monobromoacetic acid, monochloroacetic acid, tribromoacetic acid, and trichloroacetic acid. They are extracted, methylated, and then analyzed using a gas chromatograph equipped with an electron capture detector. Method validation experiments were performed to determine the method accuracy, precision, and detection limit for each of the compounds. Method detection limits for these nine haloacetic acids ranged from 0.11 to 0.45 microgram per liter. Quality-control practices include the use of blanks, quality-control samples, calibration verification standards, surrogate recovery, internal standard, matrix spikes, and duplicates.

Zazzi, Barbara C.; Crepeau, Kathryn L.; Fram, Miranda S.; Bergamaschi, Brian A.

2005-01-01

23

Direct Determination of Trace-Level Haloacetic Acids in Drinking Water by Two-1 Dimensional Ion Chromatography with Suppressed Conductivity2  

E-print Network

(chlorine, ozone,37 chlorine dioxide) react on water containing organic matter and bromide to produce1 Direct Determination of Trace-Level Haloacetic Acids in Drinking Water by Two-1 Dimensional Ion thetreatment process of drinking water, disinfectants (chlorine, ozone, chlorine dioxide)13 react on water

Boyer, Edmond

24

Impact of water stagnation in residential cold and hot water plumbing on concentrations of trihalomethanes and haloacetic acids.  

PubMed

This study demonstrates that levels of trihalomethanes (THMs) increase considerably when cold water stagnates in residential pipes and, more significantly, when water remains in the hot water tank. Levels of haloacetic acids (HAAs) increase as well in both cases, but less significantly in comparison to THMs. The study also demonstrates that in both the plumbing system and residential hot water tank, chlorinated and brominated DBP species do not behave in the same manner. Finally, the study shows that sustained use of water in households helps to maintain THM and HAA levels close to those found in water of the distribution system. The results are useful to identify methods of indoor water use that minimize population exposure to DBPs and improve DBP exposure assessment for epidemiological studies. PMID:19476964

Dion-Fortier, Annick; Rodriguez, Manuel J; Sérodes, Jean; Proulx, François

2009-07-01

25

Application of solid-phase extraction membrane disks in the determination of haloacetic acids in water by gas chromatography-mass spectrometry  

Microsoft Academic Search

Summary  Gas-Chromatography (GC) coupled with an electron capture detector (ECD) is the technique which is most used to determine haloacetic\\u000a acids (HAAs), but when chlorinated waters are analysed, many other compounds can give signals and identification can be difficult.\\u000a In this paper a gas chromatography-mass spectrometry (GC-MS) system for determining these compounds has been used to improve\\u000a identification. To reach the

D. Martínez; F. Borrull; M. Calull; J. Ruana; A. Colom

1998-01-01

26

Quantitative structure-activity relationships for the developmental toxicity of haloacetic acids in mammalian whole embryo culture.  

PubMed

Developmental toxicity in mouse whole embryo culture assay has been reported for acetic acid (AA) and a series of ten haloacetic acids, including mono-, di-, tri-fluoro (MFA, DFA, TFA), chloro (MCA, DCA, TCA), bromo (MBA, DBA, TBA), and monoiodo (MIA) acetic acids. Benchmark concentrations (BCm), calculated as the lower 95% confidence limit of molar acid concentration producing a 5% increase in embryos with neural tube defects, provided potency estimates for development of quantitative structure-activity relationships (QSARs). The best overall regression was obtained for the ten halo-acids (excluding AA) and related log (1/BCm) to the energy of the lowest unoccupied molecular orbital (Elumo) and acid dissociation constant (pKa) with a correlation coefficient of r = 0.97, and a sample size-adjusted r2 = 0.92. This QSAR suggested a common basis for the mechanism of HA activity, which would imply additivity for mixtures of these acids. Examination of QSARs for subsets of the total data set (e.g., monohaloacids) highlighted parameter relationships embedded in the total QSAR, helping to unravel the separate contributions of Elumo and pKa to the overall potency. The relevance of these parameters is discussed in terms of postulated mechanisms of developmental toxicity involving changes in intercellular pH and redox metabolism. The whole embryo assay results pertain to direct embryo exposure and toxicity without the confounding influence of maternal factors. The resulting QSAR model offers possible insight into the mechanism of embryo toxicity that will hopefully contribute to understanding of the more complex, in vivo teratogenicity problem. PMID:8910981

Richard, A M; Hunter, E S

1996-06-01

27

Cancer risk assessment on trihalomethanes and haloacetic acids in drinking water of China using disability-adjusted life years.  

PubMed

The cancer risks from exposure to trihalomethanes (THMs) and haloacetic acids (HAAs) through multiple pathways were assessed based on the result of a water quality survey in 35 major cities of China. To express the risks in disability-adjusted life years (DALYs), the excess cancer incidence estimates were combined with a two-stage disease model for calculation. The median total cancer risk of THMs and HAAs was calculated as 7.34×10(-7) DALYs per person-year (ppy), lower than the reference level of risk (10(-6)DALYsppy) set by WHO. The risk from ingestion and inhalation exposures contributed 93.6% and 6.3% of the total risk respectively, while dermal contact made a negligible contribution. The median risk of trichloroacetic acid (TCAA) (2.12×10(-7)DALYsppy) was highest among the disinfection by-products (DBPs) considered. The risk ratio of total HAAs (THAA) to total THMs (TTHM) was 1.12. The risk was highest in northeast China while lowest in northwest China. As for the 35 cities, Tianjin had the highest risk while Yinchuan had the lowest. This study attempted to use DALYs for the risk assessment of DBPs, which will provide useful information for risk comparison and prioritization of hazards in drinking water. PMID:25171513

Pan, Shenling; An, Wei; Li, Hongyan; Su, Ming; Zhang, Jinliang; Yang, Min

2014-09-15

28

Change in haloacetic acid formation potential during UV and UV/H2O2 treatment of model organic compounds.  

PubMed

Haloacetic acids (HAAs) are disinfection by-products produced by the chlorination of organic matter, including amino acids. Advanced oxidation processes are expected to be effective for the destruction of HAA precursors; however, recent studies have reported the possible failure of these processes to reduce HAA formation potential. This study examined HAA formation potential during the course of UV or UV/H2O2 treatment of three organic compounds: leucine, serine, and resorcinol. HAA formation potential decreased in the treatment of resorcinol, while the potential increased slightly in the treatment of serine and greatly increased for leucine. The chemical structure required for HAA formation was assumed to be produced during the course of UV/H2O2 treatment of leucine and serine. Also, H abstraction from the ? carbon was assumed to result from the initial degradation of leucine by the hydroxyl radical during the UV/H2O2 treatment. The hydroxyl radical may have further reacted with leucine moiety to shorten its carbon chain. This would have produced a chemical structure capable of forming HAA, thus increasing HAA formation potential. PMID:23415308

Sakai, Hiroshi; Autin, Olivier; Parsons, Simon

2013-07-01

29

Determination of haloacetic acids in swimming pool waters by membrane-protected micro-solid phase extraction.  

PubMed

In this study, a simple and efficient extraction method for determining haloacetic acids (HAAs) in swimming pool waters has been developed. HAAs are toxic organic pollutants of disinfection origin most commonly detected in swimming pool and drinking waters at trace level concentrations. For the first time, a highly efficient sorbent was developed using rice husk and used for micro-solid phase extraction (?-SPE) technique. To increase the extraction capability of rice husk silica, iron oxide was incorporated via sol-gel process. In ?-SPE device, the novel sorbent was packed and used for extraction of HAAs prior to analysis using ultra performance liquid chromatography-ultraviolet detection (UPLC-UV). Various extraction parameters were optimized to improve the extraction efficiency of ?-SPE. Under optimum conditions, linearity (coefficient of determination, r(2)?0.991 over the concentration range of 1-150 ?g/L), detection limits in the range of 0.001-0.092 ?g/L, mean recoveries up to 110% with corresponding relative standard deviations of 2-7% (n=3) had been obtained. Finally, the method was applied to swimming pool water to evaluate its feasibility. The mean concentrations for HAAs from the pool waters were in the range of 6.8 and 48.6 ?g/L which are far below the standard values set by United States Environmental Protection Agency. PMID:24075018

Nsubuga, Hakimu; Basheer, Chanbasha

2013-11-01

30

Formation of haloacetic acids, halonitromethanes, bromate and iodate during chlorination and ozonation of seawater and saltwater of marine aquaria systems.  

PubMed

This manuscript addresses identification, analysis, formation and occurrence of key disinfection byproducts (DBPs) formed during chlorination and/or ozonation of both natural seawater (NSW), and synthetic high- and low-bromide saltwater (HBSW and LBSW, respectively). In this study, several groups of water disinfection byproducts were studied, including haloacetic acids (HAAs), halonitromethanes (HNMs), bromate and iodate. Three different water systems were studied including filtered natural seawater (NSW, ca. 64.9mgL(-1) Br(-)), a high-bromide (Br(-)) saltwater (HBSW, ca. 24.8mgL(-1) Br), and low-Br(-) saltwater (LBSW, ca. 4.3mgL(-1)Br). Because ozone reacts with Cl(-) to form free chlorine in seawater and salt water systems, similar DBP patterns were observed for both chlorine and ozone oxidants. The results revealed that some HAAs and HNMs are formed at greater than 100?gL(-1) concentrations and are greatly affected by water constituents and formulations when treated with chlorine and ozone. The results showed that in low-Br(-) water salt water, chlorinated HAAs and HNMs predominated, while much greater concentrations of brominated HAAs and HNMs were produced in both natural and synthetic higher Br(-) saltwater. Concentrations of bromate and iodate were strongly impacted by factors other than Br(-) and I(-) concentrations including whether the system was open or closed. PMID:23182113

Shi, Honglan; Qiang, Zhimin; Adams, Craig

2013-03-01

31

The fate of haloacetic acids and trihalomethanes in an aquifer storage and recovery program, Las Vegas, Nevada  

USGS Publications Warehouse

The fate of disinfection byproducts during aquifer storage and recovery (ASR) is evaluated for aquifers in Southern Nevada. Rapid declines of haloacetic acid (HAA) concentrations during ASR, with associated little change in Cl concentration, indicate that HAAs decline primarily by in situ microbial oxidation. Dilution is only a minor contributor to HAA concentration declines during ASR. Trihalomethane (THM) concentrations generally increased during storage of artificial recharge (AR) water and then declined during recovery. The decline of THM concentrations during recovery was primarily from dilution of current season AR water with residual AR water remaining in the aquifer from previous ASR seasons and native ground water. In more recent ASR seasons, for wells with the longest history of ASR, brominated THMs declined during storage and recovery by processes in addition to dilution. These conclusions about THMs are indicated by THM/Cl values and supported by a comparison of measured and model predicted THM concentrations. Geochemical mixing models were constructed using major-ion chemistry of the three end-member waters to calculate predicted THM concentrations. The decline in brominated THM concentrations in addition to that from dilution may result from biotransformation processes.

Thomas, J.M.; McKay, W.A.; Colec, E.; Landmeyer, J.E.; Bradley, P.M.

2000-01-01

32

Influence of pH and ozone dose on the content and structure of haloacetic acid precursors in groundwater.  

PubMed

This study investigated the effects of pH (6-10) and ozone dose [0.4-3.0 mg O(3)/mg dissolved organic carbon (DOC)] on the content and structure of haloacetic acid (HAA) precursors in groundwater rich in natural organic matter (NOM; DOC 9.85?±?0.18 mg/L) during drinking water treatment. The raw water was ozonated in a 2 L glass column. NOM fractionation was carried out using XAD resins. HAA formation potential (HAAFP) was determined according to standard EPA Method 552. NOM characterization revealed it is mostly hydrophobic (65 % fulvic and 14 % humic acids). Hydrophobic NOM significantly influences HAA formation, as confirmed by the high HAAFP (309?±?15 ?g/L). Ozonation at pH 6-10 led to changes in NOM structure, i.e. complete humic acid oxidation, and increased the hydrophilic NOM fraction content (65-90 % achieved using 3.0 mg O(3)/mg DOC). The highest degree of NOM oxidation and HAA precursor removal was achieved at pH 10 (up to 68 % HAAFP). Ozonation pH influenced the distribution of HAA precursor content, as increasing the pH from 6 to 10 increased the reactivity of the hydrophilic fraction, with the HAAFP increasing from 19.1?±?6.0 ?g/mg DOC in raw water to 152?±?8 ?g/mg DOC in ozonated water. The degree of HAA precursor removal depends on the dominant oxidation mechanism, which is related to the applied ozone dose and the pH of the oxidation process. Ozonation at pH 10 favours the mechanism of radical NOM oxidation and was the most effective for HAAFP reduction, with the efficacy of the process improving with increasing ozone dose. PMID:22875419

Molnar, Jelena; Agbaba, Jasmina; Dalmacija, Božo; Ron?evi?, Sr?an; Prica, Miljana; Tubi?, Aleksandra

2012-09-01

33

Development of a New Column for the Measurement of Haloacetic Acids in Drinking Water by IC\\/MS and IC\\/MS\\/MS Development of a New Column for the Measurement of Haloacetic Acids in Drinking Water by IC\\/MS and IC\\/MS\\/MS  

Microsoft Academic Search

Haloacetic acids (HAAs) are among the disinfection by-products pro- duced during chlorination of water containing natural organic matter and bromide. EPA Methods 552.1 and 552.2 used to determine HAAs require tedious derivatization and multiple extraction steps followed by gas chromatography (GC) with electron capture detection (ECD) and mass spectrometry (MS). Ion chromatography-mass spectrometry (IC-MS and IC-MS\\/MS) offers a sensitive and

R. Al-Horr; C. Saini; R. Slingsby; C. Pohl

2007-01-01

34

GAS CHROMATOGRAPHY/MASS SPECTROMETRY STUDY OF MIXED HALOACETIC ACIDS FOUND IN CHLORINATED DRINKING WATER  

EPA Science Inventory

Over the last two years, our laboratory and others have identified mono-, di-, and trichloro- acetic acids as major byproducts of drinking water disinfection. n areas of the country where relatively high levels of bromine ion are naturally present in the source water, it is expec...

35

An optimized analytical method for the simultaneous detection of iodoform, iodoacetic acid, and other trihalomethanes and haloacetic acids in drinking water.  

PubMed

An optimized method is presented using liquid-liquid extraction and derivatization for the extraction of iodoacetic acid (IAA) and other haloacetic acids (HAA9) and direct extraction of iodoform (IF) and other trihalomethanes (THM4) from drinking water, followed by detection by gas chromatography with electron capture detection (GC-ECD). A Doehlert experimental design was performed to determine the optimum conditions for the five most significant factors in the derivatization step: namely, the volume and concentration of acidic methanol (optimized values ?=?15%, 1 mL), the volume and concentration of Na2SO4 solution (129 g/L, 8.5 mL), and the volume of saturated NaHCO3 solution (1 mL). Also, derivatization time and temperature were optimized by a two-variable Doehlert design, resulting in the following optimized parameters: an extraction time of 11 minutes for IF and THM4 and 14 minutes for IAA and HAA9; mass of anhydrous Na2SO4 of 4 g for IF and THM4 and 16 g for IAA and HAA9; derivatization time of 160 min and temperature at 40°C. Under optimal conditions, the optimized procedure achieves excellent linearity (R(2) ranges 0.9990-0.9998), low detection limits (0.0008-0.2 µg/L), low quantification limits (0.008-0.4 µg/L), and good recovery (86.6%-106.3%). Intra- and inter-day precision were less than 8.9% and 8.8%, respectively. The method was validated by applying it to the analysis of raw, flocculated, settled, and finished waters collected from a water treatment plant in China. PMID:23613747

Liu, Xiaolin; Wei, Xiao; Zheng, Weiwei; Jiang, Songhui; Templeton, Michael R; He, Gengsheng; Qu, Weidong

2013-01-01

36

Analysis of iodinated haloacetic acids in drinking water by reversed-phase liquid chromatography/electrospray ionization/tandem mass spectrometry with large volume direct aqueous injection.  

PubMed

A large volume direct aqueous injection method was developed for the analysis of iodinated haloacetic acids in drinking water by using reversed-phase liquid chromatography/electrospray ionization/tandem mass spectrometry in the negative ion mode. Both the external and internal standard calibration methods were studied for the analysis of monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid in drinking water. The use of a divert valve technique for the mobile phase solvent delay, along with isotopically labeled analogs used as internal standards, effectively reduced and compensated for the ionization suppression typically caused by coexisting common inorganic anions. Under the optimized method conditions, the mean absolute and relative recoveries resulting from the replicate fortified deionized water and chlorinated drinking water analyses were 83-107% with a relative standard deviation of 0.7-11.7% and 84-111% with a relative standard deviation of 0.8-12.1%, respectively. The method detection limits resulting from the external and internal standard calibrations, based on seven fortified deionized water replicates, were 0.7-2.3 ng/L and 0.5-1.9 ng/L, respectively. PMID:22658134

Li, Yongtao; Whitaker, Joshua S; McCarty, Christina L

2012-07-01

37

Direct injection ion chromatography for the control of chlorinated drinking water: simultaneous estimation of nine haloacetic acids and quantitation of bromate, chlorite and chlorate along with the major inorganic anions.  

PubMed

Most methods for the analysis of haloacetic acids published in recent years are based on ion chromatography with direct injection, employing a gradient elution with potassium hydroxide (KOH). This work reports the exploration of an alternative eluent, a buffer of sodium carbonate/sodium hydrogen carbonate, aimed at the simultaneous analysis of nine haloacetic acids along with bromate, chlorite and chlorate. The alternative of both a less alkaline eluent and a lower temperature of operation may prevent the partial decomposition of some of the haloacetic acids during the analytical process, especially the more vulnerable brominated ones. Gradient elution at temperature of 7 °C yielded the best results, with an acceptable separation of 17 analytes (which includes the major natural inorganic anions) and a good linearity. Precision ranges from 0.3 to 23.4 (% V.C.), and detection limits are within units of ?g L?¹, except for tribromoacetic acid - somewhat high in comparison with those of the official methods. Nonetheless, with the basic instrumentation setup herein described, this method may be suitable for monitoring when the drinking water treatments are to be optimized. This is especially interesting for small communities or for developing/developed countries in which regulations on disinfection by-products others than trihalomethanes are being addressed. PMID:25252348

Garcia-Villanova, Rafael J; Raposo Funcia, César; Oliveira Dantas Leite, M Vilani; Toruño Fonseca, Ivania M; Espinosa Nieto, Miguel; Espuelas India, Javier

2014-09-01

38

Determination of Haloacetic Acids in Bottled and Tap Water Sources by Dispersive Liquid-Liquid Microextraction and GC-MS Analysis  

PubMed Central

Haloacetic acids are toxic organic pollutants that can be formed as by-products of disinfection of water by chlorination. In this study, we developed a fast and efficient method for the determination of six species of these compounds in water using dispersive liquid-liquid microextraction followed by GC-MS analysis. To be suitable for GC analysis, the acidic analytes were derivatized using n-octanol. One-factor-at-a-time optimization was carried out on several factors including temperature, extraction time, amount of catalyst, and dispersive solvent. The optimized conditions were then used to determine calibration parameters. Linearity, as demonstrated by coefficient of determination, ranged between 0.9900 and 0.9966 for the concentration range of 0.05–0.57?µg/L. The proposed method has good repeatability; intraday precision was calculated as %RSD of 2.38–9.34%, while interday precision was 4.69–8.06%. The method was applied to real samples in bottled water and tap water sources. Results indicated that the total concentrations of the analytes in these sources (2.97–5.30?µg/L) were far below the maximum contaminant levels set by both the World Health Organization and the United States Environmental Protection Agency. The proposed method compared favorably with methods reported in the literature. PMID:25295305

Al-shatri, Mohsen A.; Nuhu, Abdulmumin A.; Basheer, Chanbasha

2014-01-01

39

Determination of haloacetic acids in bottled and tap water sources by dispersive liquid-liquid microextraction and GC-MS analysis.  

PubMed

Haloacetic acids are toxic organic pollutants that can be formed as by-products of disinfection of water by chlorination. In this study, we developed a fast and efficient method for the determination of six species of these compounds in water using dispersive liquid-liquid microextraction followed by GC-MS analysis. To be suitable for GC analysis, the acidic analytes were derivatized using n-octanol. One-factor-at-a-time optimization was carried out on several factors including temperature, extraction time, amount of catalyst, and dispersive solvent. The optimized conditions were then used to determine calibration parameters. Linearity, as demonstrated by coefficient of determination, ranged between 0.9900 and 0.9966 for the concentration range of 0.05-0.57 µg/L. The proposed method has good repeatability; intraday precision was calculated as %RSD of 2.38-9.34%, while interday precision was 4.69-8.06%. The method was applied to real samples in bottled water and tap water sources. Results indicated that the total concentrations of the analytes in these sources (2.97-5.30 µg/L) were far below the maximum contaminant levels set by both the World Health Organization and the United States Environmental Protection Agency. The proposed method compared favorably with methods reported in the literature. PMID:25295305

Al-shatri, Mohsen A; Nuhu, Abdulmumin A; Basheer, Chanbasha

2014-01-01

40

Electrochemical removal of haloacetic acids in a three-dimensional electrochemical reactor with Pd-GAC particles as fixed filler and Pd-modified carbon paper as cathode.  

PubMed

The reductive removal of haloacetic acids (HAAs) in a three-dimensional electrochemical continuous reactor with Pd-granular activated carbon (Pd-GAC) particles as fixed filler and Pd-modified carbon paper (Pd-C) as cathode was studied in this research. Pd-C electrode was prepared from PdCl2 via electrodeposition onto carbon paper. Pd-GAC particles were prepared by the impregnation of Pd(2+) ions onto GAC. Efficient electrocatalytic reduction of HAAs in this reactor was exhibited. Effects of current density, initial HHAs concentration, and hydraulic retention time on the HHAs removal were investigated. Under the current density of 0.3 mA/cm(2), HAAs with initial concentration of 120 ?g/L were reduced to be less than 60 ?g/L with hydraulic retention time of 20 min. Electron transfer and HAAs diffusion both played an important role in controlling the electro-reduction process under the conditions of current density less than 0.6 mA/cm(2) with an initial HAAs concentration ranging from 120 to 600 ?g/L. However, the HAAs diffusion became the primary rate-limiting step when the current density was higher than 0.6 mA/cm(2). The Pd(0) and Pd(2+) species were detected by X-ray photoelectron spectroscopy. The stability of the electrochemical reactor in the reduction removal of HAAs was also exhibited. PMID:24429102

Zhao, Xu; Li, Angzhen; Mao, Ran; Liu, Huijuan; Qu, Jiuhui

2014-03-15

41

Pyruvate remediation of cell stress and genotoxicity induced by haloacetic acid drinking water disinfection by-products.  

PubMed

Monohaloacetic acids (monoHAAs) are a major class of drinking water disinfection by-products (DBPs) and are cytotoxic, genotoxic, mutagenic, and teratogenic. We propose a model of toxic action based on monoHAA-mediated inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a target cytosolic enzyme. This model predicts that GAPDH inhibition by the monoHAAs will lead to a severe reduction of cellular ATP levels and repress the generation of pyruvate. A loss of pyruvate will lead to mitochondrial stress and genomic DNA damage. We found a concentration-dependent reduction of ATP in Chinese hamster ovary cells after monoHAA treatment. ATP reduction per pmol monoHAA followed the pattern of iodoacetic acid (IAA)?>?bromoacetic acid (BAA) > chloroacetic acid (CAA), which is the pattern of potency observed with many toxicological endpoints. Exogenous supplementation with pyruvate enhanced ATP levels and attenuated monoHAA-induced genomic DNA damage as measured with single cell gel electrophoresis. These data were highly correlated with the SN 2 alkylating potentials of the monoHAAs and with the induction of toxicity. The results from this study strongly support the hypothesis that GAPDH inhibition and the possible subsequent generation of reactive oxygen species is linked with the cytotoxicity, genotoxicity, teratogenicity, and neurotoxicity of these DBPs. PMID:23893730

Dad, Azra; Jeong, Clara H; Pals, Justin A; Wagner, Elizabeth D; Plewa, Michael J

2013-10-01

42

BIOAVAILABILITY OF HALOACETATES IN HUMAN SUBJECTS  

EPA Science Inventory

The objective of this project is to characterize the absorption, disposition and oral bioavailability of chlorinated and brominated haloacetates in human volunteers after consumption of drinking water containing a natural mixture of these compounds. We hypothesize that accurat...

43

40 CFR 141.600 - General requirements.  

Code of Federal Regulations, 2010 CFR

...compliance monitoring locations for determining compliance with maximum contaminant levels for total trihalomethanes (TTHM) and haloacetic acids (five)(HAA5). You must use an Initial Distribution System Evaluation (IDSE) to determine locations with...

2010-07-01

44

40 CFR 141.620 - General requirements.  

Code of Federal Regulations, 2010 CFR

...compliance with maximum contaminant levels based on locational running annual averages (LRAA) for total trihalomethanes (TTHM) and haloacetic acids (five)(HAA5), and for achieving compliance with maximum residual disinfectant residuals for chlorine and...

2010-07-01

45

Transports of acetate and haloacetate in Burkholderia species MBA4 are operated by distinct systems  

PubMed Central

Background Acetate is a commonly used substrate for biosynthesis while monochloroacetate is a structurally similar compound but toxic and inhibits cell metabolism by blocking the citric acid cycle. In Burkholderia species MBA4 haloacetate was utilized as a carbon and energy source for growth. The degradation of haloacid was mediated by the production of an inducible dehalogenase. Recent studies have identified the presence of a concomitantly induced haloacetate-uptake activity in MBA4. This uptake activity has also been found to transport acetate. Since acetate transporters are commonly found in bacteria it is likely that haloacetate was transported by such a system in MBA4. Results The haloacetate-uptake activity of MBA4 was found to be induced by monochloroacetate (MCA) and monobromoacetate (MBA). While the acetate-uptake activity was also induced by MCA and MBA, other alkanoates: acetate, propionate and 2-monochloropropionate (2MCPA) were also inducers. Competing solute analysis showed that acetate and propionate interrupted the acetate- and MCA- induced acetate-uptake activities. While MCA, MBA, 2MCPA, and butyrate have no effect on acetate uptake they could significantly quenched the MCA-induced MCA-uptake activity. Transmembrane electrochemical potential was shown to be a driving force for both acetate- and MCA- transport systems. Conclusions Here we showed that acetate- and MCA- uptake in Burkholderia species MBA4 are two transport systems that have different induction patterns and substrate specificities. It is envisaged that the shapes and the three dimensional structures of the solutes determine their recognition or exclusion by the two transport systems. PMID:23167477

2012-01-01

46

ACUTE SPERMATOGENIC EFFECTS OF BROMOACETIC ACIDS  

EPA Science Inventory

Chlorine and bromine, when present, can react with natural organic substances in source waters to form haloacetic acids, major by-products of chlorine disinfection. everal toxic effects including testicular damage have been attributed to chloroacetic acids but little information ...

47

Developmental toxicity of mixtures: the water disinfection by-products dichloro-, dibromo- and bromochloro acetic acid in rat embryo culture  

EPA Science Inventory

The chlorination of drinking water results in production of numerous disinfection by-products (DBPs). One of the important classes of DBPs is the haloacetic acids. We have previously shown that the haloacetic acids (HAs), dichloro (DCA), dibromo (DBA) and bromochloro (BCA) acetic...

48

FORMATION AND ENANTIOSELECTIVE BIODEGRADATION OF THE ENANTIOMERS OF BROMOCHLOROACETIC ACID  

EPA Science Inventory

Bromochloroacetic acid (BCAA) is formed by chlorination of drinking waters containing naturally occurring bromide. This haloacetic acid is a concern to public health because of suspected carcinogenicity and toxicity, and is a potential target of disinfectant byproduct regulations...

49

DRINKING WATER DISINFECTION BYPRODUCTS AND DURATION OF GESTATION  

EPA Science Inventory

Recent studies of drinking water disinfection by-products (DBPs) suggest high exposure decreases risk of preterm birth. We examined this association with total trihalomethane (TTHM) and five haloacetic acids (HAA5) among 2,041 women in a prospective pregnancy study conducted from...

50

AVOIDING PITFALLS IN THE DETERMINATION OF HALOCARBOXYLIC ACIDS: THE PHOTOCHEMISTRY OF METHYLATION  

EPA Science Inventory

Haloethanoic (haloacetic) acids are formed during chlorination of drinking water and are regulated by the Environmental Protection Agency (EPA). These compounds are normally quantified by gas chromatography with electron capture detection (GC-ECD) ad the methyl esters. EPA Meth...

51

Unusual Complex Formation and Chemical Reaction of Haloacetate Anion on the Exterior Surface of Cucurbit[6]uril in the Gas Phase  

NASA Astrophysics Data System (ADS)

Noncovalent interactions of cucurbit[6]uril (CB[6]) with haloacetate and halide anions are investigated in the gas phase using electrospray ionization ion mobility mass spectrometry. Strong noncovalent interactions of monoiodoacetate, monobromoacetate, monochloroacetate, dichloroacetate, and trichloroacetate on the exterior surface of CB[6] are observed in the negative mode electrospray ionization mass spectra. The strong binding energy of the complex allows intramolecular SN2 reaction of haloacetate, which yields externally bound CB[6]-halide complex, by collisional activation. Utilizing ion mobility technique, structures of exteriorly bound CB[6] complexes of haloacetate and halide anions are confirmed. Theoretically determined low energy structures using density functional theory (DFT) further support results from ion mobility studies. The DFT calculation reveals that the binding energy and conformation of haloacetate on the CB[6] surface affect the efficiency of the intramolecular SN2 reaction of haloacetate, which correlate well with the experimental observation.

Choi, Tae Su; Ko, Jae Yoon; Heo, Sung Woo; Ko, Young Ho; Kim, Kimoon; Kim, Hugh I.

2012-10-01

52

INHALATION EXPOSURE TO HALOACETIC ACIDS AND HALOKETONES DURING SHOWERING. (R825953)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

53

HALOACETONITRILES VS. REGULATED HALOACETIC ACIDS: ARE NITROGEN CONTAINING DBPS MORE TOXIC?  

EPA Science Inventory

Haloacetonitriles (HANs) are toxic nitrogenous drinking water disinfection by-products (N-DBPs) and are observed with chlorine, chloramine, or chlorine dioxide disinfection. Using microplate-based Chinese hamster ovary (CHO) cell assays for chronic cytotoxicity and acute genotoxi...

54

Subacute Oral Exposure to Dibromoacetic Acid Induced Immunotoxicity and Apoptosis in the Spleen and Thymus of the mice  

Microsoft Academic Search

Dibromoacetic acid (DBA) is a haloacetic acid that is present in drinking water as a by-product of chlorinated disinfection. To evaluate its potential adverse health effects, the immunotoxico- logical effects of DBA on the thymus and spleen of BALB\\/c mice were investigated. Groups of mice (10 mice per group) were administered DBA at doses of 0, 5, 20, and 50

Shuying Gao; Yan Wang; Ping Zhang; Yucui Dong; Baixiang Li

2008-01-01

55

ALTERED CRANIOFACIAL GENE EXPRESSION OF NEURULATION STAGED MOUSE EMBRYO CULTURES EXPOSED TO BROMOCHLOROACETIC ACID  

EPA Science Inventory

An unintended consequence of chemical disinfection of municipal drinking water is the production of chemical disinfection by-products (DBPs). A major class ofDBPs are haloacetic acidsthat may be found at concentrations higher than other DBPs. Bromochloroacetic acid (BCA) is a de...

56

The Effect of Water Disinfection By-products on Pregnancy Outcomes in Two Southeastern U.S. Communities  

PubMed Central

Objective To determine if exposure to DBPs during gestation increases the risk of adverse birth outcomes, specifically term small for gestational age (SGA) birth, preterm birth (PTB), and very PTB (<32 weeks gestation). Methods We used weekly measurements total trihalomethanes (TTHMs), 5 haloacetic acids (HAA5), and total organic halides (TOX) collected from two distribution systems to evaluate the associations between DBP concentrations and term SGA, PTB and very PTB using logistic regression. Results We found no associations between DBPs and term-SGA. In the site with higher concentrations of bromine-containing DBPs, we found an association between TOX and PTB; this association was larger, though less precise, for very PTB. Conclusions Our results do not support an association between TTHMs or HAA5 and the birth outcomes investigated, but an association was found between increased TOX and PTB. PMID:21915074

Horton, Bethany Jablonski; Luben, Thomas J.; Herring, Amy H.; Savitz, David A.; Singer, Philip C.; Weinberg, Howard S.; Hartmann, Katherine E.

2013-01-01

57

ALTERATION OF ESTROUS CYCLICITY BY THE DRINKING WATER DISINFECTION BY-PRODUCT DIBROMOACETIC ACID: RELATIONSHIP TO AN EFFECT ON ESTRADIOL METABOLISM?  

EPA Science Inventory

A number of chemicals formed by disinfection of municipal drinking water have been suspected to cause reproductive alterations in humans and test animals. One class of these chemicals, the haloacetic acids, have been reported to alter a number of rat testicular endpoints, includ...

58

Comparative study of a solid-phase extraction system coupled to capillary electrophoresis in the determination of haloacetic compounds in tap water  

Microsoft Academic Search

This study compares four different commercial sorbents, LC-SAX (a quaternary ammonium anion exchanger), LiChrolut EN (a highly crosslinked styrene–divinylbenzene), Envi-Carb (a graphitized carbon black) and Oasis HLB [a macroporous poly(divinylbenzene–co-N-vinylpyrrolidone) copolymer], for the solid-phase extraction (SPE) of various haloacetic compounds from aqueous samples. The recoveries with the different sorbents were studied by coupling an off-line SPE system to capillary electrophoresis

D Mart??nez; F Borrull; M Calull

1998-01-01

59

Disinfection byproduct formation resulting from settled, filtered, and finished water treated by titanium dioxide photocatalysis.  

PubMed

This study evaluated strategies targeting disinfection byproduct (DBP) mitigation using TiO2 photocatalysis with varying influent water quality. A Purifics Photo-CAT Lab reactor was used to assess total trihalomethane (TTHM) and haloacetic acid (HAA) formation as a function of photocatalytic treatment using water from a conventional coagulation/flocculation/sedimentation process, granular activated carbon filtration, and a DBP hot spot in the water distribution system. Regardless of influent water quality, photocatalysis reduced DBP precursors; however, low-energy limited photocatalysis (<5kWhm(-3)), exacerbated the production of TTHMs and HAA5s beyond initial levels. Accordingly, limited photocatalysis is not a suitable option when TTHMs and HAA5s are a concern, regardless of the level of pretreatment. Limited photocatalysis yields incomplete oxidation, wherein larger, more aromatic, humic organic compounds are broken into smaller molecular weight, less aromatic, and less humic moieties, which have considerable potential to produce DBPs. More complete mineralization of DBP precursors is obtained using extended photocatalysis (80-160kWhm(-3)), which substantially decreases DBP precursors as well as TTHM and HAA5 concentrations. In order to balance DBP mitigation, energy, and chemical usage, targeted use of TiO2 photocatalysis is necessary in a water treatment train (e.g., extended photocatalysis at a distribution system hot spot, where the volumetrically high energy requirements may be justifiable). PMID:24972073

Mayer, Brooke K; Daugherty, Erin; Abbaszadegan, Morteza

2014-12-01

60

EVALUATION OF THE CYTOTOXICITY OF DRINKING WATER DISINFECTION BYPRODUCTS (DBPS): TRIHALOMETHANES (THMS), HALONITROMETHANES (HNMS), AND HALOACETIC ACIDS (HAAS) IN NORMAL HUMAN COLON CELLS  

EPA Science Inventory

Epidemiological studies have linked the consumption of chlorinated surface waters to an increased risk of colorectal cancer. THMs and HAAs were found to increase cancer in laboratory animals, but no toxicity studies exist for the recently identified HNMs. Normal Human colonocytes...

61

Chlorodifluoroacetic acid fate and toxicity to the macrophytes Lemna gibba, Myriophyllum spicatum, and Myriophyllum sibiricum in aquatic microcosms.  

PubMed

Chlorodifluoroacetic acid (CDFA) is a novel haloacetic acid (HAA) and has been recently documented in aquatic systems. It is a suspected degradation product of the refrigerants 1,1,2-trichloro-1,1-difluoroethane (CFC-113) and 1-chloro-1,1-difluoroethane (HCFC-142b). Haloacetic acids can be phytotoxic, putatively acting through inhibition of the citric acid cycle. Replicate (n = 3) 12,000-L model aquatic ecosystems (microcosms) were dosed once at 0.5, 1, 5, and 20 mg/L of neutralized CDFA. Three microcosms served as controls. Each microcosm was stocked with eight individual apical shoots of both Myriophyllum spicatum and Myriophyllum sibiricum and sampled at regular intervals over a 42-d exposure period. The plants were assessed for the somatic endpoints of plant length, root growth, node number, and wet and dry mass and the biochemical endpoints of chlorophyll-a/b and carotenoid content as well as citric acid levels. The duckweed Lemna gibba was also introduced into these systems and monitored over a period of 14 d for wet/dry mass, plant/frond number, chlorophyll content, and growth rate. Concentrations of CDFA remained constant in the water column over the course of the fate investigation (241 d), indicating that this compound undergoes little, if any, degradation in aquatic systems. Results showed few statistically significant differences from controls for all three plant species with exposure to CDFA but no biologically relevant impacts. Overall, CDFA does not appear to pose any risk to these aquatic macrophytes at current environmental concentrations. PMID:11764159

Hanson, M L; Sibley, P K; Mabury, S A; Muir, D C; Solomon, K R

2001-12-01

62

Source Water Management for Disinfection By-Product Control using New York City's Operations Support Tool and On-Line Monitoring  

NASA Astrophysics Data System (ADS)

The United States Environmental Protection Agency's 2006 Stage 2 Disinfectant / Disinfection Byproduct Rule (DBPR) for finished drinking waters is intended to reduce overall DBP levels by limiting the levels of total trihalomethanes (TTHM) and five of the haloacetic acids (HAA5). Under Stage 2, maximum contaminant levels (MCLs), 80 ?g/L for TTHM and 60 ?g/L for HAA5, are based on a locational running annual average for individual sites instead of as the system-wide quarterly running annual average of the Stage 1 DBPR. This means compliance will have to be met at sampling locations of peak TTHM and HAA5 concentrations rather than an average across the entire system. Compliance monitoring under the Stage 2 DBPR began on April 1, 2012. The New York City (NYC) Department of Environmental Protection (DEP) began evaluating potential impacts of the Stage 2 DBPR on NYC's unfiltered water supply in 2002 by monitoring TTHM and HAA5 levels at various locations throughout the distribution system. Initial monitoring indicated that HAA5 levels could be of concern in the future, with the potential to intermittently violate the Stage 2 DBPR at specific locations, particularly those with high water age. Because of the uncertainty regarding the long-term prospect for compliance, DEP evaluated alternatives to ensure compliance, including operational changes (reducing chlorine dose, changing flow configurations to minimize water age, altering pH, altering source water withdrawals); changing the residual disinfectant from free chlorine to chloramines; and engineered treatment alternatives. This paper will discuss the potential for using DEP's Operations Support Tool (OST) and enhanced reservoir monitoring to support optimization of source water withdrawals to minimize finished water DBP levels. The OST is a state-of-the-art decision support system (DSS) to provide computational and predictive support for water supply operations and planning. It incorporates a water supply system simulation model (OASIS, HydroLogics, Inc.), reservoir water quality models, a near real-time monitoring network, and hydrologic forecasts to provide analytical support for both long-term planning and near-term operations. The OST helps managers and operators balance multiple objectives, including water supply reliability, water quality, and environmental and community release objectives. This paper will describe the results of initial testing to evaluate the potential to reduce DBP levels by managing source water withdrawals to minimize the transport of natural organic matter (NOM) precursors from upper reservoirs. Operating rules were developed that take advantage of selective withdrawal capabilities at some upstate reservoirs and the inherent flexibility of the overall water supply system, seeking to minimize DBPs within the larger framework of water supply, water quality, environmental, and regulatory objectives. The results demonstrated that there is substantial flexibility within the system to manage DBP levels, in some cases providing the potential for reductions of DBP precursors of nearly 10%. Additional research is underway that seeks to better understand the sources of natural organic matter in the NYC watershed to provide guidance for on-line monitoring to be used with the OST to support real-time operation support for DBP control.

Weiss, W. J.; Becker, W.; Schindler, S.

2012-12-01

63

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) mixture toxicity to the macrophytes Myriophyllum spicatum and Myriophyllum sibiricum in aquatic microcosms.  

PubMed

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) have been detected together in environmental water samples throughout the world. TCA may enter into aquatic systems via rainout as the degradation product of chlorinated solvents, herbicide use, as a by-product of water disinfection and from emissions of spent bleach liquor of kraft pulp mills. Sources of TFA include degradation of hydrofluorocarbons (HFCs) refrigerants and pesticides. These substances are phytotoxic and widely distributed in aquatic environments. A study to assess the risk of a binary mixture of TCA and TFA to macrophytes in aquatic microcosms was conducted as part of a larger study on haloacetic acids. M. spicatum and M. sibiricum were exposed to 0.1, 1, 3 and 10 mg/l of both TCA and TFA (neutralized with sodium hydroxide) in replicate (n = 3) 12000 l aquatic microcosms for 49 days in an one-way analysis of variance design. Each microcosm was stocked with 14 individual apical shoots per species. The plants were sampled at regular intervals and assessed for the somatic endpoints of plant length, root growth, number of nodes and wet and dry mass and the biochemical endpoints of chlorophyll-a, chlorophyll-b, carotenoid content and citric acid levels. Results indicate that there were statistically significant effects of the TCA/TFA mixture on certain pigment concentrations immediately after the start of exposure (2-7 days), but the plants showed no signs of stress thereafter. These data suggest that TCA/TFA mixtures at environmentally relevant concentrations do not pose a significant risk to these aquatic macrophytes. PMID:11878273

Hanson, Mark L; Sibley, Paul K; Mabury, Scott A; Solomon, Keith R; Muir, Derek C G

2002-02-21

64

Toxicity and Carcinogenicity of the Water Disinfection Byproduct, Dibromoacetic Acid, in Rats and Mice  

PubMed Central

Dibromoacetic acid (DBA) is a water disinfection byproduct formed by the reaction of chlorine oxidizing compounds with natural organic matter in water containing bromide. Male and female F344/N rats and B6C3F1 mice were exposed to DBA in drinking water for 2 weeks (N=5), 3 months (N=10), or 2 years (N=50). Concentrations of DBA in drinking water were 0, 125, 250, 500, 1,000, and 2,000 mg/L in the 2-week and 3-month studies, and 0, 50, 500, and 1,000 mg/L in the 2-year studies. Toxic effects of DBA in the prechronic studies were detected in the liver (hepatocellular cytoplasmic vacuolization in rats and mice) and testes (delayed spermiation and atypical residual bodies in male rats and mice, and atrophy of the germinal epithelium in rats). In the 2-year studies, neoplasms were induced at multiple sites in rats and mice exposed to DBA; these included mononuclear cell leukemia and abdominal cavity mesothliomas in rats, and neoplasms of the liver (hepatocellular adenoma or carcinoma and hepatoblastoma) and lung (alveolar adenoma or carcinoma) in mice. The increase in incidence of hepatocellular neoplasms in male mice was significant even at the lowest exposure concentration of 50 mg/L, which is equivalent to an average daily dose of approximately 5 mg/kg. These studies provide critical information for future re-evaluations of health-based drinking water standards for haloacetic acids. PMID:17157429

Melnick, Ronald L.; Nyska, Abraham; Foster, Paul M.; Roycroft, Joseph H.; Kissling, Grace E.

2007-01-01

65

Analyse structurale des dérivés fonctionnels des acides carboxyliques Partie III. Acétate d'éthyle, dérivés ?-halogénés  

NASA Astrophysics Data System (ADS)

Methylene bending mode analysis of ethyl esters of acetic and haloacetic acids XCH 2CO 2C 2H 5 where X=H( I), F( II), Cl( III),Br ( IV) and I( V) reveals that in the dissolved state (CCl 4) these compounds have conformations induced by rotating motion of the XCH 2 and C 2H 5 groups (( II), ( III) and ( IV)) or by C 2H 5 group rotation exclusively (( I) and ( V)). In the last case, ( I) exists in gauche and anti conformations while ( V) occurs in gauche—gauche and gauche—anti conformations. A theoretical study of compounds ( I), ( II) and ( III) by the PCILO method and Onsager formalism leads to the following conclusion The conformers of ( I) have a dihedral angle (H 3)C?C(H 2)?O?C of 70° (gauche conformer) and 180° (anti conformer). For ( II) and ( III), there are four stable conformers whose dihedral angle ? 3=(H 3)C?C(H 2)?O?C and ?=X?C?C?O values are in agreement with C 2H 5 and CH 2X group orientations found in experimental analysis.

Maury, Catherine; Petrissans, Jean

1991-09-01

66

Genotoxic and clastogenic effects of monohaloacetic acid drinking water disinfection by-products in primary human lymphocytes.  

PubMed

The haloacetic acids (HAAs) are the second-most prevalent class of drinking water disinfection by-products formed by chemical disinfectants. Previous studies have determined DNA damage and repair of HAA-induced lesions in mammalian and human cell lines; however, little is known of the genomic DNA and chromosome damage induced by these compounds in primary human cells. The aim of this study was to evaluate the genotoxic and clastogenic effects of the monoHAA disinfection by-products in primary human lymphocytes. All monoHAAs were genotoxic in primary human lymphocytes, the rank order of genotoxicity and cytotoxicity was IAA > BAA > CAA. After 6 h of repair time, only 50% of the DNA damage (maximum decrease in DNA damage) was repaired compared to the control. This demonstrates that primary human lymphocytes are less efficient in repairing the induced damage by monoHAAs than previous studies with mammalian cell lines. In addition, the monoHAAs induced an increase in the chromosome aberration frequency as a measurement of the clastogenic effect of these compounds. These results coupled with genomic technologies in primary human cells and other mammalian non-cancerous cell lines may lead to the identification of biomarkers that may be employed in feedback loops to aid water chemists and engineers in the overall goal of producing safer drinking water. PMID:23602619

Escobar-Hoyos, Luisa F; Hoyos-Giraldo, Luz Stella; Londoño-Velasco, Elizabeth; Reyes-Carvajal, Ingrid; Saavedra-Trujillo, Diana; Carvajal-Varona, Silvio; Sánchez-Gómez, Adalberto; Wagner, Elizabeth D; Plewa, Michael J

2013-06-15

67

Photodecomposition of humic acid and natural organic matter in swamp water using a TiO(2)-coated ceramic foam filter: potential for the formation of disinfection byproducts.  

PubMed

This paper reports on the photodecomposition of aqueous humic acid (HA) by a TiO(2)-coated ceramic foam filter (TCF) reactor and on the potential for the formation of disinfection byproducts (DBPs) upon chlorination of the photocatalytically treated solutions. This photocatalytic reactor can also be applied to the removal of natural organic matter (NOM) in swamp waters. The proposed photocatalytic reaction system was operated as per standardized methodologies. First, the ability of the TCF to decompose HA (a representative compound of NOM) was evaluated from the changes in the total organic carbon (TOC) and UV(254) with the reaction time. Remarkably, TOC removal and UV(254) values ranging from 44% to 61% and from 60% to 83%, respectively, were achieved. The potential for the formation of DBPs (total trihalomethane and total haloacetic acid) by chlorination of the phototreated solution was strongly dependent on the TOC removal and UV(254) values in the solution. The degree of photodecomposition of NOMs in the swamp water samples and the DBP formation potential showed similar trends as in the case of the standard solutions containing HA. The method used in this study could be effectively used to evaluate the efficiency of TCF for reducing HA and NOM, while suppressing the formation of DBP products. PMID:22921646

Mori, Masanobu; Sugita, Tsuyoshi; Mase, Akinori; Funatogawa, Takahiro; Kikuchi, Masaru; Aizawa, Kazuhiko; Kato, Shigekazu; Saito, Yoichi; Ito, Tsukasa; Itabashi, Hideyuki

2013-01-01

68

Field level evaluation and risk assessment of the toxicity of dichloroacetic acid to the aquatic macrophytes Lemna gibba, Myriophyllum spicatum, and Myriophyllum sibiricum.  

PubMed

Dichloroacetic acid (DCA), a haloacetic acid, is a common contaminant of aquatic ecosystems. A study to investigate potential phytotoxic effects on rooted and floating macrophytes (Myriophyllum spicatum, M. sibiricum, and Lemna gibba) was conducted. Replicate 12,000 L outdoor microcosms (n = 3) were treated with 3, 10, 30, and 100 mg/L of DCA that had been neutralized to the sodium salt, plus controls. Plants were sampled regularly over 21 days and assessed for a variety of endpoints including plant growth, root growth, number of nodes, wet and dry mass, chlorophyll-a, chlorophyll-b, carotenoids, and citrate levels. EC10, EC25, and EC50 values were calculated for each endpoint that exhibited a concentration-response. Overall, M. sibiricum was slightly more sensitive than M. spicatum to DCA exposure. The most sensitive plant endpoints were wet mass and plant length. Pigments showed no response with exposure to DCA. The probability of current concentrations of DCA in Canadian lake water and Swiss river waters exceeding thresholds of toxicity derived from single species effect measure distributions (EC10s) is < 0.01%. The use of effect measure distributions holds promise as a new risk assessment technique for aquatic plants. Currently, environmental levels of DCA do not pose a risk to these plants. PMID:12706393

Hanson, Mark L; Sibley, Paul K; Mabury, Scott A; Muir, Derek C G; Solomon, Keith R

2003-05-01

69

Acid rain  

Microsoft Academic Search

Acid precipitation is a global problem. The effects were first seen in Europe; it affects the Great Lakes and the Midwest because higher-than-normal levels of acidity in rain are found in these areas. Several bays of the Great Lakes are now known to receive substantial runoff from freshwater streams that have been made acidic by acid rains. These areas may

1979-01-01

70

Spatial variation of disinfection by-product concentrations: exposure assessment implications.  

PubMed

The use of public water system (PWS) average trihalomethane (THM) and haloacetic acid (HAA) concentrations as surrogates of "personal" exposures in epidemiological studies of disinfection by-products (DBPs) may result in exposure misclassification bias from various sources of measurement error including intra-system variation of DBPs. Using 2000-2004 data from 107 PWSs in Massachusetts, we assessed two approaches for characterizing DBP spatial variability by identifying PWSs with low spatial variability (LSV) and examining differences in LSV across DBP groups and by type of source water and primary disinfectant. We also used spatial differences to examine the association between THM concentrations and indices of social disadvantage; however, we found no correlations or statistically significant differences based on the available data. We observed similar patterns for the percentage of quarterly sampling dates with LSV across different types of source water for all DBPs but not across disinfectants. We found there was little overlap between sites classified as having LSV across different DBP groups. In the main analysis, we found moderate correlations between both approaches (?(THM4) = 0.55; ?(BrTHM) = 0.64; ?(HAA5) = 0.67); although Method 1 (based on concentration differences between samples) may be better suited for identifying PWSs for inclusion in epidemiological studies because it is more easily adapted to study-specific exposure gradients than Method 2 (based on categorical exposure percentiles). These data reinforce the need to consider different exposure assessment approaches when examining the spatial variation of multiple DBP surrogates as they can represent different DBP mixtures. PMID:23993731

Evans, Amanda M; Wright, J Michael; Meyer, Amy; Rivera-Núñez, Zorimar

2013-10-15

71

REPRODUCTIVE AND DEVELOPMENTAL EFFECTS SCREENING STUDIES  

EPA Science Inventory

Several DBPs, particularly the disubstituted haloacetic acids (e.g. dibromoacetic acid, bromochloroacetic acid), have been shown to produce reproductive and developmental toxicity in laboratory animals. In 1993, an expert panel convened by the EPA and the International Life Scien...

72

Rosmarinic acid  

Microsoft Academic Search

Rosmarinic acid is an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid. It is commonly found in species of the Boraginaceae and the subfamily Nepetoideae of the Lamiaceae. However, it is also found in species of other higher plant families and in some fern and hornwort species. Rosmarinic acid has a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory and

Maike Petersen; Monique S. J Simmonds

2003-01-01

73

Shikimic Acid  

NSDL National Science Digital Library

The molecule for this month comes from the article Isolation of Shikimic Acid from Star Aniseed by Richard Payne and Michael Edmonds. Shikimic acid plays a key role in the biosynthesis of many important natural products including aromatic amino acids, alkaloids, phenolics, and phenylpropanoids. It plays such an important role that one of the key biosynthetic pathways is referred to as the shikimate pathway.

74

Acid rain  

Microsoft Academic Search

For the past five years, scientists at the Univ. of Colorado have been measuring acid precipitation in a subalpine watershed of the Colorado Rockies. Their measurements of snow and rain and creek water show a strong trend of increasing acidity that is traceable to the chemical reactions of burning fossil fuels. Possible effects of acid precipitation on the watershed's aquatic

Caile

2009-01-01

75

Rosmarinic acid.  

PubMed

Rosmarinic acid is an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid. It is commonly found in species of the Boraginaceae and the subfamily Nepetoideae of the Lamiaceae. However, it is also found in species of other higher plant families and in some fern and hornwort species. Rosmarinic acid has a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory and antioxidant. The presence of rosmarinic acid in medicinal plants, herbs and spices has beneficial and health promoting effects. In plants, rosmarinic acid is supposed to act as a preformed constitutively accumulated defence compound. The biosynthesis of rosmarinic acid starts with the amino acids L-phenylalanine and L-tyrosine. All eight enzymes involved in the biosynthesis are known and characterised and cDNAs of several of the involved genes have been isolated. Plant cell cultures, e.g. from Coleus blumei or Salvia officinalis, accumulate rosmarinic acid in amounts much higher than in the plant itself (up to 36% of the cell dry weight). For this reason a biotechnological production of rosmarinic acid with plant cell cultures has been proposed. PMID:12482446

Petersen, Maike; Simmonds, Monique S J

2003-01-01

76

Acid rain  

SciTech Connect

This book presents the proceedings of the third annual conference sponsored by the Acid Rain Information Clearinghouse (ARIC). Topics covered include: Legal aspects of the source-receptor relationship: an energy perspective; Scientific uncertainty, agency inaction, and the courts; and Acid rain: the emerging legal framework.

White, J.C. (Cornell University, Ithaca, NY (US))

1988-01-01

77

Tranexamic Acid  

MedlinePLUS

Tranexamic acid comes as a tablet to take by mouth. It is usually taken with or without food three times a day for up to 5 days during monthly menstruation. You should begin taking this medication each month when your period starts. Do not take tranexamic acid when you do not have a period. Take ...

78

Acid rain  

Microsoft Academic Search

The causes and effects of acid rain are detailed. Sulfur dioxide and nitrogen dioxide emissions from anthropogenic sources are the primary causative agents. These emissions are transported over long distances and transformed into sulfates and nitrates and washed out of the atmosphere. Trends in acidity in precipitation water are reviewed for eastern portions of Canada and the U.S. Adverse effects

R. E. Ghelardi; B. L. Murphy

2009-01-01

79

Acid Rain  

Microsoft Academic Search

Measurements of the acidity of rain and snow reveal that in parts of the eastern U.S. and of western Europe precipitation has changed from a nearly neutral solution 200 years ago to a dilute solution of sulfuric and nitric acids today. The trend is a result of the emission of sulfur and nitrogen oxides to the atmosphere accompanying the rise

Gene E. Likens; Richard F. Wright; James N. Galloway; Thomas J. Butler

1979-01-01

80

Acid test  

NSDL National Science Digital Library

Baking soda can be used as an indicator of how much acid a substance contains. Lemons and limes have more acid in them than grapefruits and oranges. Indophenol can be used as an indicator of how much vitamin C is in a substance.

Olivia Worland (Purdue University;Biological Sciences)

2008-06-06

81

Domoic Acid  

NSDL National Science Digital Library

This online student report discusses the chemistry of domoic acid, a biotoxin that is produced by the diatom Psuedo-nitzschia and associated with Amnesiac Shellfish Poisoning (ASP). In addition to a descriptive summary and images, the report links to other areas of interest related to domoic acid poisoning including signs and symptoms, modes of action, and treatment.

Bailey, Christina; Kohlen, Corinne

2010-02-10

82

Asparagusic acid.  

PubMed

Asparagusic acid (1,2-dithiolane-4-carboxylic acid) is a simple sulphur-containing 5-membered heterocyclic compound that appears unique to asparagus, though other dithiolane derivatives have been identified in non-food species. This molecule, apparently innocuous toxicologically to man, is the most probable culprit responsible for the curious excretion of odorous urine following asparagus ingestion. The presence of the two adjacent sulphur atoms leads to an enhanced chemical reactivity, endowing it with biological properties including the ability to substitute potentially for ?-lipoic acid in ?-keto-acid oxidation systems. This brief review collects the scattered data available in the literature concerning asparagusic acid and highlights its properties, intermediary metabolism and exploratory applications. PMID:24099657

Mitchell, Stephen C; Waring, Rosemary H

2014-01-01

83

The effect of boiling water on disinfection by-product exposure  

Microsoft Academic Search

Chloraminated and chlorinated waters containing bromide were used to determine the impact of boiling on disinfection by-product (DBP) concentrations. No significant changes were detected in the concentrations of the dihalogenated haloacetic acids (DXAAs) (i.e., dichloro-, bromochloro-, dibromoacetic acid) upon boiling of chloraminated water, whereas the levels of the trihalogenated haloacetic acids (TXAAs) (i.e., trichloro- (TCAA), bromodichloro- (BDCAA), dibromochloroacetic acid (DBCAA))

Stuart W. Krasner; J. Michael Wright

2005-01-01

84

Acid Rain  

NSDL National Science Digital Library

Due to the presence of dissolved gases such as carbon dioxide, rainfall is naturally acidic. The release of other gases and chemicals such as sulfur dioxide during the combustion of coal and oil can cause rainfall to become even more acidic, sometimes to the point of toxicity. In this activity, students will measure the pH of local rainfall to see what effect these gases have in their region. They will also check an online resource to see how the releases of acid rain-causing chemicals have varied over the past 20 years, and answer questions about the information they uncover.

Fox, Chris

85

Acid fog  

SciTech Connect

Fog in areas of southern California previously thought to be pollution-free has been shown to have a pH as low as 1.69. It has been found to be most acidic after smoggy days, suggesting that it forms on the aerosol associated with the previously exiting smog. Studies on Whiteface Mountain in the Adirondacks show that fog water is often 10 times as acidic as rainwater. As a result of their studies, California plans to spend $4 million on acid deposition research in the coming year. (JMT)

Hileman, B.

1983-03-01

86

ACID RAIN  

EPA Science Inventory

Acid precipitation has become one of the major environmental problems of this decade. It is a challenge to scientists throughout the world. Researchers from such diverse disciplines as plant pathology, soil science, bacteriology, meteorology and engineering are investigating diff...

87

Acidic precipitation  

SciTech Connect

At the International Symposium on Acidic Precipitation, over 400 papers were presented, and nearly 200 of them are included here. They provide an overview of the present state of the art of acid rain research. The Conference focused on atmospheric science (monitoring, source-receptor relationships), aquatic effects (marine eutrophication, lake acidification, impacts on plant and fish populations), and terrestrial effects (forest decline, soil acidification, etc.).

Martin, H.C.

1987-01-01

88

Acid sphingomyelinase.  

PubMed

The enzyme acid sphingomyelinase catalyzes the hydrolysis of sphingomyelin to ceramide. The importance of the enzyme for cell functions was first recognized in Niemann-Pick disease type A and B, the genetic disorders with a massive accumulation of sphingomyelin in many organs. Studies in the last years demonstrated that the enzyme also has an important role in cell signalling. Thus, the acid sphingomyelinase has a central function for the re-organization of molecules within the cell upon stimulation and thereby for the response of cells to stress and the induction of cell death but also proliferation and differentiation. Here, we discuss the current state of the art of the structure, regulation, and function of the acid sphingomyelinase. PMID:23579450

Henry, Brian; Ziobro, Regan; Becker, Katrin Anne; Kolesnick, Richard; Gulbins, Erich

2013-01-01

89

Salicylic acids  

PubMed Central

Salicylic acid is well known phytohormone, emerging recently as a new paradigm of an array of manifestations of growth regulators. The area unleashed yet encompassed the applied agriculture sector to find the roles to strengthen the crops against plethora of abiotic and biotic stresses. The skipped part of integrated picture, however, was the evolutionary insight of salicylic acid to either allow or discard the microbial invasion depending upon various internal factors of two interactants under the prevailing external conditions. The metabolic status that allows the host invasion either as pathogenesis or symbiosis with possible intermediary stages in close systems has been tried to underpin here. PMID:22301975

Hayat, Shamsul; Irfan, Mohd; Wani, Arif; Nasser, Alyemeni; Ahmad, Aqil

2012-01-01

90

Acid Stomach  

NSDL National Science Digital Library

This Science NetLinks lesson is intended for a high-school, introductory chemistry class or health class. The lesson begins with an article on the history of the development of aspirin. Students will then complete a lab that compares the reaction of regular aspirin, buffered aspirin, and enteric aspirin in neutral, acidic, and basic solutions. They will then analyze the results of the experiment to gain insight into how this information was used by researchers to solve some of the problems associated with aspirin. To complete the lesson, students must understand acids and bases.

Science Netlinks;

2003-08-07

91

Acid rain  

Microsoft Academic Search

The book describes numerous environmental problems which are the result of emissions from coal combustion, petroleum products combustion, petroleum refining, and non-ferrous smelting. The effects of acid rain on soils, plants, water, aquatic ecosystems, and building materials are described. Studies are discussed which show that wind currents are carrying emissions to locations far from the source, with social, economic, and

Ostmann; R. Jr

1982-01-01

92

Acid rain  

SciTech Connect

An overview is presented of acid rain and the problems it causes to the environment worldwide. The acidification of lakes and streams is having a dramatic effect on aquatic life. Aluminum, present in virtually all forest soils, leaches out readily under acid conditions and interferes with the gills of all fish, some more seriously than others. There is evidence of major damage to forests in European countries. In the US, the most severe forest damage appears to be in New England, New York's Adirondacks, and the central Appalachians. This small region is part of a larger area of the Northeast and Canada that appears to have more acid rainfall than the rest of the country. It is downwind from major coal burning states, which produce about one quarter of US SO/sub 2/ emissions and one sixth of nitrogen oxide emissions. Uncertainties exist over the causes of forest damage and more research is needed before advocating expensive programs to reduce rain acidity. The President's current budget seeks an expansion of research funds from the current $30 million per year to $120 million.

Not Available

1984-06-01

93

DISINFECTION BY-PRODUCT FORMATION BY ALTERNATIVE DISINFECTANTS AND REMOVAL BY GRANULAR ACTIVATED CARBON  

EPA Science Inventory

The effects of the use of the alternative disinfectants on the formation of halogenated disinfection by–products (DBPs) including total organic halide, trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, chloral hydrate, and chloropicrin, were examined along ...

94

DISINFECTION BY-PRODUCT FORMATION BY ALTERNATIVE DISINFECTANTS AND REMOVAL BY GRANULAR ACTIVATED CARBON  

EPA Science Inventory

The effects of the use of the alternative disinfectants on the formation of halogenated disinfection by-products (DBPS) including total organic halide, trihalomethanes, haloacetic acids, haloacentonitriles, haloketones, chloral hydrate, and chloropicrin, were examined along with ...

95

EARLY CRANIOFACIAL DEVELOPMENT: LIFE AMONG THE SIGNALS  

EPA Science Inventory

Early Craniofacial Development: Life Among the Signals. Sid Hunter and Keith Ward. Reproductive Toxicology Division, NHEERL, US EPA, RTP, NC, 27711 Haloacetic acids (HAA) are chemicals formed during drinking water disinfection and present in finished tap water. Exposure o...

96

FEASIBILITY STUDY OF THE UTILITY OF THE ICR DATABASE FOR STUDYING THE REPRODUCTIVE EFFECTS OF DISINFECTION BY-PRODUCTS IN DRINKING WATER  

EPA Science Inventory

This study assessed the feasibility of conducting an epidemiologic study of the relationship between DBPs and adverse reproductive outcomes, using quarterly monitoring data of trihalomethanes and haloacetic acids from the EPA's Information Collection Rule (ICR) data base. Emphas...

97

Domoic Acid  

NSDL National Science Digital Library

This highly detailed chemical information page features domoic acid, a toxin associated with Amnesic shellfish poisoning and naturally produced by the red algae Chondria armata and diatoms of the genus Pseudo-nitzschia. Created by the International Programme on Chemical Safety, this web page organizes information under the following sections: Name, Summary, Physio-Chemical Properties, Uses, Routes of Entry, Kinetics, Toxicology, Toxicological and Biomedical Investigations, Clinical Effects, Management, Illustrative Cases, Additional Information, References, and Authors.

Inchem; Safety, International P.

98

Acid Ocean  

NSDL National Science Digital Library

The I2I-Acid Ocean virtual lab is an e-learning activity where students become virtual scientists studying the impact of ocean acidification on sea urchin larval growth. Students recreate a real, up-to-date climate change experiment. They also learn important general scientific principles, such as the importance of sample size and numbers of replicates, and discuss what this research into a specific impact of climate change may mean for the future of our oceans. There is a French translation available.

99

Methylmalonic acid blood test  

MedlinePLUS

... acid is a substance produced when proteins (called amino acids) in the body break down. A test can ... Cederbaum S, Berry GT. Inborn errors of carbohydrate, ammonia, amino acid, and organic acid metabolism. In: Gleason CA, Devaskar ...

100

Electrochemical oxidation of reverse osmosis concentrate on boron-doped diamond anodes at circumneutral and acidic pH.  

PubMed

Electrochemical processes have been widely investigated for degrading organic contaminants present in wastewater. This study evaluated the performance of electrochemical oxidation using boron-doped diamond (BDD) electrodes by forming OH() for the treatment of reverse osmosis concentrate (ROC) from secondary-treated wastewater effluents. Since oxidation by OH() and active chlorine species (HClO/ClO(-)) is influenced by pH, the electrochemical oxidation of ROC was evaluated at controlled pH 6-7 and at pH 1-2 (no pH adjustment). A high concentration of chloride ions in the ROC enhanced the oxidation, and 7-11% of Coulombic efficiency for chemical oxygen demand (COD) removal was achieved with 5.2 Ah L(-1) of specific electrical charge. Complete COD removal was observed after 5.2 and 6.6 Ah L(-1), yet the corresponding dissolved organic carbon (DOC) removal was only 48% (at acidic pH) and 59% (at circumneutral pH). Although a higher operating pH seemed to enhance the participation of OH() in oxidation mechanisms, high concentrations of chloride resulted in the formation of significant concentrations of adsorbable organic chlorine (AOCl) after electrochemical oxidation at both pH. While adsorbable organic bromine (AOBr) was degraded at a higher applied electrical charge, a continuous increase in AOCl concentration (up to 0.88 mM) was observed until the end of the experiments (i.e. 10.9 Ah L(-1)). In addition, total trihalomethanes (tTHMs) and total haloacetic acids (tHAAs) were further degraded with an increase in electrical charge under both pH conditions, to final total concentrations of 1 and 4 ?M (tTHMs), and 12 and 22 ?M (tHAAs), at acidic and circumneutral pH, respectively. In particular, tHAAs were still an order of magnitude above their initial concentration in ROC after further electrooxidation. Where high chloride concentrations are present, it was found to be necessary to separate chloride from ROC prior to electrochemical oxidation in order to avoid the formation of chlorinated by-products. PMID:22995242

Bagastyo, Arseto Y; Batstone, Damien J; Kristiana, Ina; Gernjak, Wolfgang; Joll, Cynthia; Radjenovic, Jelena

2012-11-15

101

Understanding Acid Rain  

ERIC Educational Resources Information Center

The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

Damonte, Kathleen

2004-01-01

102

Brnsted Acids The Strongest Isolable Acid**  

E-print Network

Brønsted Acids The Strongest Isolable Acid** Mark Juhasz, Stephan Hoffmann, Evgenii Stoyanov, Kee-Chan Kim, and Christopher A. Reed* Acids based on carborane anions as conjugate bases (Figure 1) are a new class of Brønsted (protic) acids, notable for their "strong yet gentle" qualities.[1] For example

Reed, Christopher A.

103

Acid rain  

SciTech Connect

Acid rain, says Boyle is a chemical leprosy eating into the face of North America and Europe, perhaps the major ecological problem of our time. Boyle describes the causes and scope of the phenomenon; the effects on man, wildlife, water, and our cultural heritage. He probes the delays of politicians and the frequent self-serving arguments advanced by industry in the face of what scientists have proved. The solutions he offers are to strengthen the Clean Air Act and require emission reductions that can be accomplished by establishing emission standards on a regional or bubble basis, burn low-sulfur coal, install scrubbers at critical plants, and invest in alternative energy sources. 73 references, 1 figure.

Boyle, R.H.; Boyle, R.A.

1983-01-01

104

New method of acidizing or acid fracturing: crosslinked acid gels  

SciTech Connect

Acid polymer gels having pH less than one have been crosslinked for retarding the chemical and physical activity of hydrochloric acid on calcareous formations. Hydrochloric acid concentrations from .0025 to 28% have been successfully crosslinked. This stimulation fluid offers high viscosity with adequate shear stability, perfect support for proppants, and clay stabilization. Additionally, the fluid provides effective fluid loss control and retardation of acid reaction enabling live acid to penetrate deeper into the formation for better formation conductivity and practically a residue-free break for rapid clean-up of the well after the job. Results of lab and field tests show the acid crosslinked system to be an effective stimulation fluid for acidizing and acid fracturing in calcareous and sandstone formations having low formation permeability.

Pabley, A.S.; Holcomb, D.L.

1980-01-01

105

Rediscovering Arsenoacetic Acid.  

E-print Network

??Arsonoacetic acid, H?O?As¹CH?COOH, and arsenoacetic acid, punitively [AsVCH?COOH]? have been synthesised according to historical literature methods, and have been characterised using modern techniques. Arsonoacetic acid… (more)

Wilson, Peter Stanley

2009-01-01

106

Organic acids tunably catalyze carbonic acid decomposition.  

PubMed

Density functional theory calculations predict that the gas-phase decomposition of carbonic acid, a high-energy, 1,3-hydrogen atom transfer reaction, can be catalyzed by a monocarboxylic acid or a dicarboxylic acid, including carbonic acid itself. Carboxylic acids are found to be more effective catalysts than water. Among the carboxylic acids, the monocarboxylic acids outperform the dicarboxylic ones wherein the presence of an intramolecular hydrogen bond hampers the hydrogen transfer. Further, the calculations reveal a direct correlation between the catalytic activity of a monocarboxylic acid and its pKa, in contrast to prior assumptions about carboxylic-acid-catalyzed hydrogen-transfer reactions. The catalytic efficacy of a dicarboxylic acid, on the other hand, is significantly affected by the strength of an intramolecular hydrogen bond. Transition-state theory estimates indicate that effective rate constants for the acid-catalyzed decomposition are four orders-of-magnitude larger than those for the water-catalyzed reaction. These results offer new insights into the determinants of general acid catalysis with potentially broad implications. PMID:24933150

Kumar, Manoj; Busch, Daryle H; Subramaniam, Bala; Thompson, Ward H

2014-07-10

107

Acid Rain Study Guide.  

ERIC Educational Resources Information Center

Acid rain is a complex, worldwide environmental problem. This study guide is intended to aid teachers of grades 4-12 to help their students understand what acid rain is, why it is a problem, and what possible solutions exist. The document contains specific sections on: (1) the various terms used in conjunction with acid rain (such as acid

Hunger, Carolyn; And Others

108

Formic Acid Mechanical,  

E-print Network

and engineering. Products will range from starch, to polylactic acid, to corn fiber, to motor fuels. ProgressiveFormic Acid Fire Ant Starch Mechanical, Industrial Chemical, Petroleum Biological What Do systems. Fire ants make formic acid. U of I researchers are developing fuel cells that use formic acid (1

Illinois at Urbana-Champaign, University of

109

Sulphuric Acid Manufacture  

Microsoft Academic Search

The raw material for sulphuric acid manufacture is clean SO2 gas. It comes from (i) burning molten by-product sulphur; (ii) roasting or smelting metal sulphide concentrates, and (iii) decomposing contaminated organic chemical process sulphuric acid catalyst. Efficient gas cleaning is required for metallurgical and contaminated acid decomposition gases, especially the former. Sulphuric acid is made from SO2 gas by (i)

W. G. Davenport; M. J. King; B. Rogers; A. Weissenberger

2006-01-01

110

Asphaltene damage in matrix acidizing  

E-print Network

were acidized with three stage treatments of 15% hydrochloric acid (HCl), 12% HCL-3% hydrofluoric acid (HF) and 15% HCL. No additives were used in the acid. Comparisons were made between cores acidized with a variety of saturating fluids. Petrographic...

Hinojosa, Roberto Antonio

2012-06-07

111

Quantity of acid in acid fog  

SciTech Connect

This communication notes the actual magnitude of the acidity in acidic fog particles and suggests a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air.

Deal, W.J.

1983-07-01

112

New bioactive fatty acids.  

PubMed

Many oxygenated fatty acids are bioactive compounds. Nocardia cholesterolicum and Flavobacterium DS5 convert oleic acid to 10 hydroxy stearic acid and linoleic acid to 10-hydroxy-12(Z)-octadecanoic acid. Pseudomonas aeruginosa PR3 converts oleic acid to the new compounds, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) through 10-hydroxy-8-octadecenoic acid, and racinoleic acid to 7,10,12-trihydroxy-8-octadecenoic acid. DOD showed antibacterial activity including against food-borne pathogens. Bacillus megaterium ALA2 converted n-6 and n-3 PUFAs to many new oxygenated fatty acids. For example: linoleic acid was converted to12,13-epoxy-9-octadecenoic acid and then to 12,13-dihydroxy-9-octadecenoic acid (12,13-DHOA). From here, there are two bioconversion pathways. The major pathway is: 12,13-DHOA --> 12,13,17-trihydroxy-9(S)-octadecenoic acid (THOA) --> 12,17;13,17-diepoxy-16-hydroxy-9(Z)-octadecenoic acid (DEOA) --> 7-hydroxy-DEOA. The minor pathway is: 12,13-DHOA --> 12,13,16-THOA --> 12-hydroxy-13,16-epoxy-9(Z)-octadecenoic acid. 12,13,17-THOA has anti-plant pathogenic fungal activity. The tetrahydrofuranyl moiety is known in anti cancer drugs. Strain ALA2 also converts other n-3 and n-6 PUFAs such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) to many new oxygenated unsaturated fatty acid products. All of these new products have high potential for antimicrobial agents or biomedical applications. We also screened 12 Mortierella fungal strains from the ARS Culture Collection for the production of bioactive fatty acids such as dihomo-gama-linolenic acid (DGLA) and arachidonic acid. All of the strains tested produced AA and DGLA from glucose or glycerol. The top five AA producers (mg AA/g CDW) were in the following order: M. alpina > M. zychae > M. hygrophila > M. minutissima > M. parvispora. Both AA and DGLA are important natural precursors of a large family of prostaglandin and thromboxane groups. PMID:18296335

Hou, Ching T

2008-01-01

113

Fatty acid analogs  

DOEpatents

In one aspect, a radioactively labeled analog of a fatty acid which is capable of being taken up by mammalian tissue and which exhibits an in vivo beta-oxidation rate below that with a corresponding radioactively labeled fatty acid.

Elmaleh, David R. (Newton Center, MA); Livni, Eli (Brookline, MA)

1985-01-01

114

Plasma amino acids  

MedlinePLUS

Plasma amino acids is a screening test done on infants that looks at the amounts of amino ... Laboratory error High or low amounts of individual plasma amino acids must be considered with other information. ...

115

Citric acid urine test  

MedlinePLUS

... usually done while you are on a normal diet. Ask your health care provider for more information. ... A low level of citric acid may mean renal tubular acidosis and a ... acid levels: A high carbohydrate diet Estrogen therapy Vitamin D

116

Plant fatty acid hydroxylases  

DOEpatents

This invention relates to plant fatty acyl hydroxylases. Methods to use conserved amino acid or nucleotide sequences to obtain plant fatty acyl hydroxylases are described. Also described is the use of cDNA clones encoding a plant hydroxylase to produce a family of hydroxylated fatty acids in transgenic plants. In addition, the use of genes encoding fatty acid hydroxylases or desaturases to alter the level of lipid fatty acid unsaturation in transgenic plants is described.

Somerville, Chris (Portola Valley, CA); Broun, Pierre (Burlingame, CA); van de Loo, Frank (Lexington, KY)

2001-01-01

117

Acid rain agreement  

Microsoft Academic Search

Scientific working groups from Canada and the US have been established to prepare for acid rain negotiations scheduled for June 1981. The groups will take air samples and estimate impact of acid rain on the environment, determine the precise origin of acid rain, and develop a strategy for abatement. Some constraints on the negotiations are costs (potentially $400-500 million for

R. J. SMITH

1980-01-01

118

[alpha]-Oxocarboxylic Acids  

ERIC Educational Resources Information Center

Several [alpha]-oxocarboxylic acids play key roles in metabolism in plants and animals. However, there are inconsistencies between the structures as commonly portrayed and the reported acid ionization constants, which result because the acids are predominantly hydrated in aqueous solution; that is, the predominant form is RC(OH)[subscript 2]COOH…

Kerber, Robert C.; Fernando, Marian S.

2010-01-01

119

What Is Acid Rain?  

ERIC Educational Resources Information Center

Acid rain is the collective term for any type of acidified precipitation: rain, snow, sleet, and hail, as well as the presence of acidifying gases, particles, cloud water, and fog in the atmosphere. The increased acidity, primarily from sulfuric and nitric acids, is generated as a by-product of the combustion of fossil fuels such as coal and oil.…

Likens, Gene E.

2004-01-01

120

Acid (and Base) Rainbows  

NSDL National Science Digital Library

Learners use red cabbage juice and pH indicator paper to test the acidity and basicity of household materials. The activity links this concept of acids and bases to acid rain and other pollutants. Resource contains vocabulary definitions and suggestions for assessment, extensions, and scaling for different levels of learners.

Kolenbrander, Amy; Yowell, Janet; Mach, Natalie; Zarske, Malinda S.; Carlson, Denise; Perez, Sharon

2004-01-01

121

Quantity of acid in acid fog  

SciTech Connect

The chemical composition of fog particles has become of considerable interest, because of both the possibility of interpreting atmospheric- chemistry processes in fog particles in terms of the principles of aqueous chemistry and the potential health effects of species present in fog particles. The acidity of fog particles has received wide attention. This communication noted the actual magnitude of the excess acidity in acidic fog particles and suggested a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air. (DP)

Deal, W.J.

1983-07-01

122

Acid Strengths of Some Substituted Picric Acids.  

National Technical Information Service (NTIS)

The aqueous dissociation constants for a number of substituted picric acids and related compounds were determined spectrophotometrically, and the values obtained correlated with the mid-equivalence potentials obtained by half-neutralization in acetone sol...

P. J. Pearce, R. J. J. Simkins

1968-01-01

123

Abscisic Acid ELISA: Organic Acid Interference 1  

PubMed Central

Consideration must be exercised in determination of buffers and solutions used when carrying out enzyme-linked immunosorbent assays (ELISAs). A commercial monoclonal antibody kit for abscisic acid (Idetek, Inc.) gives significant false-positives with tricarboxylic acid cycle intermediates. The organic acids or contaminants interfered with ELISA assays for ABA as indicated by deviations in the slopes of standard curves of ABA in the organic acids. The interference, in the case of ?-ketoglutarate, was caused by a contaminant. Of the organic buffers tested—Tris, Tricine, and Hepes—only Hepes showed false-positive ABA. In addition, we present data indicating the presence of ABA in commercial mannitol and provide a simple procedure for removal of the ABA. PMID:16667202

Belefant, Helen; Fong, Franklin

1989-01-01

124

Editorial: Acid precipitation  

SciTech Connect

This editorial focuses on acid rain and the history of public and governmental response to acid rain. Comments on a book by Gwineth Howell `Acid Rain and Acid Waters` are included. The editor feels that Howells has provide a service to the environmental scientific community, with a textbook useful to a range of people, as well as a call for decision makers to learn from the acid rain issue and use it as a model for more sweeping global environmental issues. A balance is needed among several parameters such as level of evidence, probability that the evidence will lead to a specific direction and the cost to the global community. 1 tab.

NONE

1995-09-01

125

Amino acid analysis  

NASA Technical Reports Server (NTRS)

The process and apparatus for qualitative and quantitative analysis of the amino acid content of a biological sample are presented. The sample is deposited on a cation exchange resin and then is washed with suitable solvents. The amino acids and various cations and organic material with a basic function remain on the resin. The resin is eluted with an acid eluant, and the eluate containing the amino acids is transferred to a reaction vessel where the eluant is removed. Final analysis of the purified acylated amino acid esters is accomplished by gas-liquid chromatographic techniques.

Winitz, M.; Graff, J. (inventors)

1974-01-01

126

EXTRACTIONOFTERVALENTLANTHANIDESWITH ACIDIC ORGANOPHOSPHORUS COMPOUNDS  

Microsoft Academic Search

The equilibrium.extraction behavior for a series of tervalent lanthanide ions (Ln) using a chloroform solution containing di(2-ethyl-hexyl) phosphoric acid (HDEHP), diphenylphosphinic acid (HDPP), dibutylphosphorothioic acid (HDBPT), di-n-octylphosphorodithoic acid (HDOPDT), or di(2-ethylhexyl)phosphorodithioic acid (HDEHPDT), either alone or combined with adduct forming agents is studied. The extracted species are Ln(DEHP) 3(HDEHP) 3, Ln(DPP)3 (HDPP)3, Ln(DBPT)3, and are Ln(DBPT)3(HDERP)3 in the presence of

Shoji Motomizu; Henry Freiser

1985-01-01

127

Selective extraction of succinic acid from binary mixture of succinic acid and acetic acid  

Microsoft Academic Search

In production of succinic acid by fermentation, succinic acid and acetic acid are co-produced. To purify the succinic acid from binary-acid mixture of succinic acid and acetic acid, the tertiary amine-based extraction was used. In 1-octanol, the selectivity for succinic acid was proportional to the chain length of tertiary amine. But, the distribution of acids into organic phase was low

Yeon Ki Hong; Won Hi Hong; Ho Nam Chang

2000-01-01

128

Demospongic Acids Revisited  

PubMed Central

The well-known fatty acids with a ?5,9 unsaturation system were designated for a long period as demospongic acids, taking into account that they originally occurred in marine Demospongia sponges. However, such acids have also been observed in various marine sources with a large range of chain-lengths (C16–C32) and from some terrestrial plants with short acyl chains (C18–C19). Finally, the ?5,9 fatty acids appear to be a particular type of non-methylene-interrupted fatty acids (NMA FAs). This article reviews the occurrence of these particular fatty acids in marine and terrestrial organisms and shows the biosynthetic connections between ?5,9 fatty acids and other NMI FAs. PMID:21116406

Kornprobst, Jean-Michel; Barnathan, Gilles

2010-01-01

129

NRPSs and amide ligases producing homopoly(amino acid)s and homooligo(amino acid)s.  

PubMed

Microorganisms are capable of producing a wide variety of biopolymers. Homopoly(amino acid)s and homooligo(amino acid)s, which are made up of only a single type of amino acid, are relatively rare; in fact, only two homopoly(amino acid)s have been known to occur in nature: poly(?-L-lysine) (?-PL) and poly(?-glutamic acid) (?-PGA). Bacterial enzymes that produce homooligo(amino acid)s, such as L-?-lysine-, L-valine-, L-leucine-, L-isoleucine-, L-methionine-, and L-glutamic acid-oligopeptides and poly(?-l-glutamic acid) (?-PGA) have recently been identified, as well as ?-PL synthetase and ?-PGA synthetase. This article reviews the current knowledge about these unique enzymes producing homopoly(amino acid)s and homooligo(amino acid)s. PMID:23817633

Hamano, Yoshimitsu; Arai, Toshinobu; Ashiuchi, Makoto; Kino, Kuniki

2013-08-01

130

Acid rain reports  

NASA Astrophysics Data System (ADS)

Three independent reports on acid precipitation issued in June reinforce each other and, taken together, support those seeking immediate action to curb man-generated acid deposition in northeastern North America by reducing emissions of sulfur and nitrogen oxides. The Interagency Task Force on Acid Precipitation report concluded that manmade pollution is to blame for acid precipitation problems in the northeastern United States. A National Research Council (NRC) committee stated that reducing the manmade emissions of sulfur and nitrogen oxides will result in a proportional reduction in the deposition of acid precipitation. And an acid rain panel assembled by the White House Office of Science and Technology Policy (OSTP) called for immediate action to curb the emissions despite incomplete scientific data.

Richman, Barbara T.

131

Lewis acid organocatalysts.  

PubMed

Abstract The term Lewis acid catalysts generally refers to metal salts like aluminium chloride, titanium chloride and zinc chloride. Their application in asymmetric catalysis can be achieved by the addition of enantiopure ligands to these salts. However, not only metal centers can function as Lewis acids. Compounds containing carbenium, silyl or phosphonium cations display Lewis acid catalytic activity. In addition, hypervalent compounds based on phosphorus and silicon, inherit Lewis acidity. Furthermore, ionic liquids, organic salts with a melting point below 100 degrees C, have revealed the ability to catalyze a range of reactions either in substoichiometric amount or, if used as the reaction medium, in stoichiometric or even larger quantities. The ionic liquids can often be efficiently recovered. The catalytic activity of the ionic liquid is explained by the Lewis acidic nature of their cations. This review covers the survey of known classes of metal-free Lewis acids and their application in catalysis. PMID:21494948

Sereda, Oksana; Tabassum, Sobia; Wilhelm, René

2010-01-01

132

Lewis Acid Organocatalysts  

NASA Astrophysics Data System (ADS)

The term Lewis acid catalysts generally refers to metal salts like aluminium chloride, titanium chloride and zinc chloride. Their application in asymmetric catalysis can be achieved by the addition of enantiopure ligands to these salts. However, not only metal centers can function as Lewis acids. Compounds containing carbenium, silyl or phosphonium cations display Lewis acid catalytic activity. In addition, hypervalent compounds based on phosphorus and silicon, inherit Lewis acidity. Furthermore, ionic liquids, organic salts with a melting point below 100 °C, have revealed the ability to catalyze a range of reactions either in substoichiometric amount or, if used as the reaction medium, in stoichiometric or even larger quantities. The ionic liquids can often be efficiently recovered. The catalytic activity of the ionic liquid is explained by the Lewis acidic nature of their cations. This review covers the survey of known classes of metal-free Lewis acids and their application in catalysis.

Sereda, Oksana; Tabassum, Sobia; Wilhelm, René

133

Acid Rain Learning Activities  

NSDL National Science Digital Library

These suggestions for activities allow students to learn about acid deposition in new and interactive ways, both in and out of the classroom. The suggestions are for individuals and small groups, the class as a whole, or for field trips. Students may contact local experts about acid rain issues, investigate the energy sources used to generate electricity by their local power companies, collect cartoons about acid rain and air pollution, or play the roles of scientists or interested parties involved in investigations of acid rain issues. Field trip ideas include visiting a local museum or science center to see exhibits or resources on acid rain, and visiting a local cemetary to examine the effects of acid rain on the headstones.

134

Bile Acid Metabolism  

Microsoft Academic Search

\\u000a Bile acids are physiological agents that facilitate biliary secretion of lipids and metabolites, and intestinal absorption\\u000a of fat and nutrients. Bile acids are also signaling molecules that activate nuclear receptors and cell signaling pathways\\u000a to regulate hepatic lipid metabolism and homeostasis. Bile acids are synthesized from cholesterol in the liver, stored in\\u000a the gallbladder, secreted to the intestine and reabsorbed

John Y. L. Chiang

135

Acid rain on Bermuda  

Microsoft Academic Search

Increased acidity of precipitation due to combustion of fossil fuels has been well documented for both the eastern USA1 and Canada2. The SO2 and NOxemitted by the burning of coal, natural gas, fuel oil and petrol are oxidized in the atmosphere to sulphuric and nitric acids which subsequently give rise to acid precipitation1. However, the SO2 and NOx emitted, and

Timothy Jickells; Anthony Knap; Thomas Church; James Galloway; John Miller

1982-01-01

136

Acid-Base Solutions  

NSDL National Science Digital Library

How do strong and weak acids differ? Use lab tools on your computer to find out! Dip the paper or the probe into solution to measure the pH, or put in the electrodes to measure the conductivity. Then see how concentration and strength affect pH. Can a weak acid solution have the same pH as a strong acid solution?

Simulations, Phet I.; Lancaster, Kelly; Malley, Chris; Loeblein, Patricia; Parson, Robert; Perkins, Kathy

2010-09-01

137

DEOXYRIBONUCLEIC ACID HYBRIDS OF ACETIC ACID BACTERIA  

PubMed Central

De Ley, J. (State University, Ghent, Belgium), and S. Friedman. Deoxyribonucleic acid hybrids of acetic acid bacteria. J. Bacteriol. 88:937–945. 1964.—Deuterated N15-labeled deoxyribonucleic acid (DNA) from Acetobacter aceti (mesoxydans 4) forms hybrids with ordinary DNA from other species of this genus (A. xylinum, A. pasteurianus, A. estunensis, and possibly A. xylinoides) when the guanine plus cytosine base composition does not vary by more than 1 to 2%. Beyond this limit (A. aceti Ch31 and A. muciparus 5) no hybrids are formed. The hybrids are apparently derived from an asymmetrical part of the compositional distribution. The results lend strength to the concept of a genetic species rather than to a division of a genus into sharply separated species, based on small phenotypic differences. Taxonomic implications are discussed. PMID:14219057

De Ley, J.; Friedman, S.

1964-01-01

138

Uric Acid Test  

MedlinePLUS

... purine metabolism . Metastatic cancer, multiple myeloma , leukemias , and cancer chemotherapy can cause increased production of uric acid. Chronic renal disease , acidosis , toxemia of pregnancy , and alcoholism can cause ...

139

Molecular Structure of Fumaric acid  

NSDL National Science Digital Library

Fumaric acid is odorless and colorless or white crystalline powder with a fruit acid taste. Fumaric acid is used as a substitute of tartaric acid in beverages and baking powders and as a replacement for citric acid in fruits drinks. It is also used as antioxidant to prevent rancidity in butter, cheese, powdered milk, and other foodstuff. In addition, fumaric acid is a chemical intermediate in the manufacture of pharmaceuticals, synthetic resins and plastics. Fumaric acid can be prepared by catalytic oxidation of benzene or by bacterial action on glucose and it is involved in the production of energy from food. Fumaric acid (known as trans-butanedioic acid) is the trans isomer of maleic acid (also called cis-butanedioic acid). Fumaric acid is more stable than maleic acid and can be prepared by heating maleic acid.

2004-11-05

140

Regioselective hydroxylation of quinolinic acid, lutidinic acid and isocinchomeronic acid by resting cells of pyridine dicarboxylic acid-degrading microorganisms  

Microsoft Academic Search

Microorganisms aerobically degrading quinolinic acid, lutidinic acid or isocinchomeronic acid were isolated and the microbial regioselective hydroxylation of these pyridine dicarboxylic acids was studied. Alcaligenes sp. UK21 cells converted quinolinic acid into 6-hydroxypicolinic acid, suggesting the involvement of two enzyme reactions catalyzing hydroxylation at position C6 and decarboxylation at position C3 of quinolinic acid. Resting cells of Alcaligenes sp. UK21

A. Uchida; T. Yoshida; M. Ogawa; T. Nagasawa

2003-01-01

141

Neutralizing Acids and Bases  

NSDL National Science Digital Library

In this activity, students will use their knowledge of color changes with red cabbage indicator to neutralize an acidic solution with a base and then neutralize a basic solution with an acid. This website includes a student activity sheet and additional student readings.

2010-01-01

142

(Acid rain workshop)  

Microsoft Academic Search

The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment

1990-01-01

143

Acid rain: Controllable?  

Microsoft Academic Search

Acid rain is one of a growing number of environmental issues in which impacts are far removed from the source o f the irritants. Those who suffer may differ in geographical area from those who benefit from the activity which releases pollution to the atmosphere. Like the issue concerning the depletion of ozone by manufactured chemicals, the acid rain issue

Lester Machta

1983-01-01

144

Mounting acid rain  

Microsoft Academic Search

The incidence of acid rain at some distance from the initial source of pollution is expected to increase as more plants are converted to burn coal and stacks are built higher to relieve local pollution problems. The alkaline soils of the West neutralize most of the effects of acid rain, making the problem less acute than in the eastern US.

1979-01-01

145

EFFECTS OF ACID PRECIPITATION  

EPA Science Inventory

Recent reviews of available data indicate that precipitation in a large region of North America is highly acidic when its pH is compared with the expected pH value of 5.65 for pure rain water in equilibrium with CO2. A growing body of evidence suggests that acid rain is responsib...

146

Iodinated humic acids  

NASA Astrophysics Data System (ADS)

Humic acids are iodinated by elemental iodine and, if the iodine is present as iodide, by peroxidase-mediated reactions. It is demonstrated that iodination of humic acids leads to a product with a uniform distribution of iodine. It could not be unambiguously verified whether the enzymatically mediated iodination is a direct reaction between a peroxidase-iodine complex and the humic acid molecule or a two-step reaction in which the enzyme creates elemental iodine, which consecutively reacts with the humic acid. Based on a simple model of a reaction between sites in the humic acids available for iodination and the electrophilic iodinating species, it was concluded that the reaction should be described as an equilibrium with a logarithmic equilibrium constant of approximately 4. The number of sites available for iodination was, in the humic acids studied, determined to be approximately 4×10-4 per gram humic acid. The different parameters influencing the enzymatically controlled iodination of humic acids are discussed.

Christiansen, Jesper V.; Carlsen, Lars

147

Controlling acid rain  

E-print Network

High concentrations of sulfuric and nitric acid in raTn fn the northeastern USA are caused by the large scale combustion of fossil fuels within this region. Average precipitation acidity is pH 4.2, but spatial and temporal ...

Fay, James A.

1983-01-01

148

Bile acid transporters  

PubMed Central

In liver and intestine, transporters play a critical role in maintaining the enterohepatic circulation and bile acid homeostasis. Over the past two decades, there has been significant progress toward identifying the individual membrane transporters and unraveling their complex regulation. In the liver, bile acids are efficiently transported across the sinusoidal membrane by the Na+ taurocholate cotransporting polypeptide with assistance by members of the organic anion transporting polypeptide family. The bile acids are then secreted in an ATP-dependent fashion across the canalicular membrane by the bile salt export pump. Following their movement with bile into the lumen of the small intestine, bile acids are almost quantitatively reclaimed in the ileum by the apical sodium-dependent bile acid transporter. The bile acids are shuttled across the enterocyte to the basolateral membrane and effluxed into the portal circulation by the recently indentified heteromeric organic solute transporter, OST?-OST?. In addition to the hepatocyte and enterocyte, subgroups of these bile acid transporters are expressed by the biliary, renal, and colonic epithelium where they contribute to maintaining bile acid homeostasis and play important cytoprotective roles. This article will review our current understanding of the physiological role and regulation of these important carriers. PMID:19498215

Dawson, Paul A.; Lan, Tian; Rao, Anuradha

2009-01-01

149

ACID AEROSOLS ISSUE PAPER  

EPA Science Inventory

The report evaluates scientific information on direct health effects associated with exposure to acid aerosols. The present report is not intended as a complete and detailed review of all literature pertaining to acid aerosols. Rather, an attempt has been made to focus on the eva...

150

Lead-acid batteries  

Microsoft Academic Search

A method of producing a lead-acid battery capable of activation by the addition of electrolyte thereto, comprises the steps of: starting with a battery container accommodating at least one pack of battery plate grids having insulating separators interposed between adjacent grids, each of said grids carrying the lead-acid battery paste required to produce a positive or a negative battery plate

J. A. Bant; V. J. Raban

1980-01-01

151

Urobilinogen AscorbicAcid  

E-print Network

Date Lot # Bilirubin Urobilinogen Ketone AscorbicAcid Glucose Protein Blood pH Nitrite Leukocytes Specific Gravity hCG: Method Lot # Acetest® (Ketone): Lot # Clinitest® (Glucose): Lot # Ictotest®(Bilirubin AND DATA ENTRY FORMS #12;Date Lot # Bilirubin Urobilinogen Ketone AscorbicAcid Glucose Protein Blood p

Rodriguez, Carlos

152

Acid Rain Revisited  

NSDL National Science Digital Library

The results of a long term study of the effects of acidic deposition in the Northeast were published in Bioscience this week, and they suggest that forests, lakes, and streams of the Northeastern US are not recovering from the toxic effects of acid rain despite significant cuts in the power plant emissions of sulfur dioxide and nitrogen oxide -- two major contributors to the problem. "Acid rain," more accurately called acidic deposition, causes toxic forms of aluminum to concentrate in soil and water, vital calcium and magnesium to be leached from trees, and surface waters to become inhospitable to aquatic biota. The study showed that, after 30 years of federally mandated air emission reductions, sulfur dioxide emissions have decreased while nitrogen oxide emissions have remained the same and that acidic deposition-related problems continue to plague New York and New England.

Sanders, Hilary C.

2001-01-01

153

Acid rain trends summarized  

NASA Astrophysics Data System (ADS)

In the northeastern United States, the acidity of precipitation has changed little in recent years, although the acidity is increasing in other regions. That's the latest word from a comprehensive review by the U.S. Geological Survey (USGS) of more than 200 published reports of acid rain research from the past 30 years. The report contributes to the controversy over whether increased sulfur emissions from Midwest powerplants increase the acidity of precipitation in the Northeast.“When the results of the many individual studies are combined, they show that acidification of precipitation in the Northeast, which has the most damaging level of acidity on a regional basis, occurred primarily before the mid-1950's and has been largely stabilized since the mid-1960s,” said John T. Turk, a research hydrologist at the USGS Denver office and author of the 18-page summary report.

154

Fatty Acid Production from Amino Acids and ?-Keto Acids by Brevibacterium linens BL2†  

PubMed Central

Low concentrations of branched-chain fatty acids, such as isobutyric and isovaleric acids, develop during the ripening of hard cheeses and contribute to the beneficial flavor profile. Catabolism of amino acids, such as branched-chain amino acids, by bacteria via aminotransferase reactions and ?-keto acids is one mechanism to generate these flavorful compounds; however, metabolism of ?-keto acids to flavor-associated compounds is controversial. The objective of this study was to determine the ability of Brevibacterium linens BL2 to produce fatty acids from amino acids and ?-keto acids and determine the occurrence of the likely genes in the draft genome sequence. BL2 catabolized amino acids to fatty acids only under carbohydrate starvation conditions. The primary fatty acid end products from leucine were isovaleric acid, acetic acid, and propionic acid. In contrast, logarithmic-phase cells of BL2 produced fatty acids from ?-keto acids only. BL2 also converted ?-keto acids to branched-chain fatty acids after carbohydrate starvation was achieved. At least 100 genes are potentially involved in five different metabolic pathways. The genome of B. linens ATCC 9174 contained these genes for production and degradation of fatty acids. These data indicate that brevibacteria have the ability to produce fatty acids from amino and ?-keto acids and that carbon metabolism is important in regulating this event. PMID:15528496

Ganesan, Balasubramanian; Seefeldt, Kimberly; Weimer, Bart C.

2004-01-01

155

Conjugated Fatty Acid Synthesis  

PubMed Central

Conjugated linolenic acids (CLNs), 18:3 ?9,11,13, lack the methylene groups found between the double bonds of linolenic acid (18:3 ?9,12,15). CLNs are produced by conjugase enzymes that are homologs of the oleate desaturases FAD2. The goal of this study was to map the domain(s) within the Momordica charantia conjugase (FADX) responsible for CLN formation. To achieve this, a series of Momordica FADX-Arabidopsis FAD2 chimeras were expressed in the Arabidopsis fad3fae1 mutant, and the transformed seeds were analyzed for the accumulation of CLN. These experiments identified helix 2 and the first histidine box as a determinant of conjugase product partitioning into punicic acid (18:3 ?9cis,11trans,13cis) or ?-eleostearic acid (18:3 ?9cis,11trans,13trans). This was confirmed by analysis of a FADX mutant containing six substitutions in which the sequence of helix 2 and first histidine box was converted to that of FAD2. Each of the six FAD2 substitutions was individually converted back to the FADX equivalent identifying residues 111 and 115, adjacent to the first histidine box, as key determinants of conjugase product partitioning. Additionally, expression of FADX G111V and FADX G111V/D115E resulted in an approximate doubling of eleostearic acid accumulation to 20.4% and 21.2%, respectively, compared with 9.9% upon expression of the native Momordica FADX. Like the Momordica conjugase, FADX G111V and FADX D115E produced predominantly ?-eleostearic acid and little punicic acid, but the FADX G111V/D115E double mutant produced approximately equal amounts of ?-eleostearic acid and its isomer, punicic acid, implicating an interactive effect of residues 111 and 115 in punicic acid formation. PMID:22451660

Rawat, Richa; Yu, Xiao-Hong; Sweet, Marie; Shanklin, John

2012-01-01

156

Total syntheses of cis-cyclopropane fatty acids: dihydromalvalic acid, dihydrosterculic acid, lactobacillic acid, and 9,10-methylenehexadecanoic acid.  

PubMed

cis-Cyclopropane fatty acids (cis-CFAs) are widespread constituents of the seed oils of subtropical plants, membrane components of bacteria and protozoa, and the fats and phospholipids of animals. We describe a systematic approach to the synthesis of enantiomeric pairs of four cis-CFAs: cis-9,10-methylenehexadecanoic acid, lactobacillic acid, dihydromalvalic acid, and dihydrosterculic acid. The approach commences with Rh2(OAc)4-catalyzed cyclopropenation of 1-octyne and 1-decyne, and hinges on the preparative scale chromatographic resolution of racemic 2-alkylcycloprop-2-ene-1-carboxylic acids using a homochiral Evan's auxiliary. Saturation of the individual diastereomeric N-cycloprop-2-ene-1-carbonylacyloxazolidines, followed by elaboration to alkylcyclopropylmethylsulfones, allowed Julia-Kocienski olefination with various ?-aldehyde-esters. Finally, saponification and diimide reduction afforded the individual cis-CFA enantiomers. PMID:25321346

Shah, Sayali; White, Jonathan M; Williams, Spencer J

2014-12-14

157

Synthesis of (+)- and (?)-Phaselic Acid  

Microsoft Academic Search

The synthesis of both enantiomers of phaselic acid (2-O-caffeoylmalate) is described. The previously unreported acetate protected caffeic acid anhydride was used with appropriately protected malic acid derivatives as coupling partners to provide fully protected phaselic acid. Sequential unmasking of the protecting groups afforded phaselic acid in an acceptable overall yield.

Wayne E. Zeller

2012-01-01

158

The Completely Sequenced Plasmid pEST4011 Contains a Novel IncP1 Backbone and a Catabolic Transposon Harboring tfd Genes for 2,4-Dichlorophenoxyacetic Acid Degradation  

PubMed Central

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterium Achromobacter xylosoxidans subsp. denitrificans strain EST4002 contains plasmid pEST4011. This plasmid ensures its host a stable 2,4-D+ phenotype. We determined the complete 76,958-bp nucleotide sequence of pEST4011. This plasmid is a deletion and duplication derivative of pD2M4, the 95-kb highly unstable laboratory ancestor of pEST4011, and was self-generated during different laboratory manipulations performed to increase the stability of the 2,4-D+ phenotype of the original strain, strain D2M4(pD2M4). The 47,935-bp catabolic region of pEST4011 forms a transposon-like structure with identical copies of the hybrid insertion element IS1071::IS1471 at the two ends. The catabolic regions of pEST4011 and pJP4, the best-studied 2,4-D-degradative plasmid, both contain homologous, tfd-like genes for complete 2,4-D degradation, but they have little sequence similarity other than that. The backbone genes of pEST4011 are most similar to the corresponding genes of broad-host-range self-transmissible IncP1 plasmids. The backbones of the other three IncP1 catabolic plasmids that have been sequenced (the 2,4-D-degradative plasmid pJP4, the haloacetate-catabolic plasmid pUO1, and the atrazine-catabolic plasmid pADP-1) are nearly identical to the backbone of R751, the archetype plasmid of the IncP1 ? subgroup. We show that despite the overall similarity in plasmid organization, the pEST4011 backbone is sufficiently different (51 to 86% amino acid sequence identity between individual backbone genes) from the backbones of members of the three IncP1 subgroups (the ?, ?, and ? subgroups) that it belongs to a new IncP1subgroup, the ? subgroup. This conclusion was also supported by a phylogenetic analysis of the trfA2, korA, and traG gene products of different IncP1 plasmids. PMID:15489427

Vedler, Eve; Vahter, Merle; Heinaru, Ain

2004-01-01

159

Sulfuric Acid on Europa  

NASA Technical Reports Server (NTRS)

Frozen sulfuric acid on Jupiter's moon Europa is depicted in this image produced from data gathered by NASA's Galileo spacecraft. The brightest areas, where the yellow is most intense, represent regions of high frozen sulfuric acid concentration. Sulfuric acid is found in battery acid and in Earth's acid rain.

This image is based on data gathered by Galileo's near infrared mapping spectrometer.

Europa's leading hemisphere is toward the bottom right, and there are enhanced concentrations of sulfuric acid in the trailing side of Europa (the upper left side of the image). This is the face of Europa that is struck by sulfur ions coming from Jupiter's innermost moon, Io. The long, narrow features that crisscross Europa also show sulfuric acid that may be from sulfurous material extruded in cracks.

Galileo, launched in 1989, has been orbiting Jupiter and its moons since December 1995. JPL manages the Galileo mission for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

1999-01-01

160

Acid recovery from waste sulfuric acid by diffusion dialysis  

Microsoft Academic Search

In the process of sulfuric acid production from pyrite, there is a lot of waste acid produced in fume washing with dilute\\u000a acid. Acid recovery from this sort of waste sulfuric acid by diffusion dialysis is studied in the paper. The mass transfer\\u000a dialysis coefficient of sulfuric acid of the membrane AFX is measured, the effect of the flowrate of

Guiqing Zhang; Qixiu Zhang; Kanggen Zhou

1999-01-01

161

Strongly Acidic Auxin Indole-3-Methanesulfonic Acid  

PubMed Central

A radiochemical synthesis is described for [14C]indole-3-methanesulfonic acid (IMS), a strongly acidic auxin analog. Techniques were developed for fractionation and purification of IMS using normal and reverse phase chromatography. In addition, the utility of both Fourier transform infrared spectrometry and fast atom bombardment mass spectrometry for analysis of IMS has been demonstrated. IMS was shown to be an active auxin, stimulating soybean hypocotyl elongation, bean first internode curvature, and ethylene production. IMS uptake by thin sections of soybean hypocotyl was essentially independent of solution pH and, when applied at a 100 micromolar concentration, IMS exhibited a basipetal polarity in its transport in both corn coleoptile and soybean hypocotyl sections. [14C]IMS should, therefore, be a useful compound to study fundamental processes related to the movement of auxins in plant tissues and organelles. PMID:16664007

Cohen, Jerry D.; Baldi, Bruce G.; Bialek, Krystyna

1985-01-01

162

Ceric acid decontamination of nuclear reactors  

SciTech Connect

This patent describes a composition, it consists of water; about 0.5 to about 3% by weight of a ceric acid selected from the group consisting of tetrasulfato ceric acid, hexasulfamato ceric acid, hexaperchlorato ceric acid, and mixtures thereof; and about 1 to about 5% by weight of an inorganic acid. The inorganic acid is sulfuric acid when the ceric acid is tetrasulfato ceric acid, sulfamic acid when the ceric acid is hexasulfamato ceric acid, perchloric acid when the ceric acid is a mixture selected from the group consisting of tetrasulfato ceric acid, hexasulfamato ceric acid, and hexaperchlorato ceric acid.

Murray, A.P; Slater, C.G.; White, R.W.

1989-11-14

163

Stomach acid test  

MedlinePLUS

Gastric acid secretion test ... The test is done after a period of not eating so that fluid is all that remains in the ... the stomach through the esophagus (food pipe). To test the ability of the cells in the stomach ...

164

ACID RAIN CONTROL OPTIONS  

EPA Science Inventory

The paper discusses acid rain control options available to the electric utility industry. They include coal switching, flue gas desulfurization, and such emerging lower cost technologies as Limestone Injection Multistage Burners (LIMB) and Advanced Silicate (ADVACATE) both develo...

165

Acid-Base Tutorial  

NSDL National Science Digital Library

Website for anyone wanting to become more familiar with the physiology of acid-base balance in clinical medicine. Several pages are interactive. Numerical results are accompanied by text interpretations to facilitate recognition and understanding.

MD Alan W. Grogono (Tulane University School of Medicine Dept. of Anesthesiology)

2002-06-01

166

Folic acid in diet  

MedlinePLUS

... leafy vegetables Dried beans and peas (legumes) Citrus fruits and juices Fortified means that vitamins have been added to the food. Many foods are now fortified with folic acid, including enriched breads, cereals, flours, cornmeals, pastas, rice, ...

167

Acid Lipase Disease  

MedlinePLUS

... Acid Lipase Disease Information Page Synonym(s): Cholesterol Ester Storage Disease, Wolman’s Disease Table of Contents (click to ... include waxes, oils, and cholesterol. Two rare lipid storage diseases are caused by the deficiency of the ...

168

(Acid rain workshop)  

SciTech Connect

The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment Program, the United Nations Economic and Social Commission for Asia and the Pacific, and the World Bank. Papers presented on the first day discussed how the experience gained with acid rain in North America and Europe might be applied to the Asian situation. Papers describing energy use projections, sulfur emissions, and effects of acid rain in several Asian countries were presented on the second day. The remaining time was allotted to discussion, planning, and writing plans for a future research program.

Turner, R.S.

1990-12-05

169

Aminolevulinic Acid Topical  

MedlinePLUS

... under the skin that result from exposure to sunlight and can develop into skin cancer) of the ... acid will make your skin very sensitive to sunlight (likely to get sunburn). Avoid exposure of treated ...

170

Fatty Acid Carcass Mapping  

E-print Network

FATTY ACID CARCASS MAPPING A Thesis by STACEY NICOLE TURK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2008... Major Subject: Animal Science FATTY ACID CARCASS MAPPING A Thesis by STACEY NICOLE TURK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE...

Turk, Stacey N.

2010-01-14

171

Acid-base chemistry  

SciTech Connect

The book is not a research compendium and there are no references to the literature. It is a teaching text covering the entire range of undergraduate subject matter dealing with acid-base chemistry (some of it remotely) as taught in inorganic, analytical, and organic chemistry courses. The excellent chapters VII through IX deal in detail with the quantitative aspects of aqueous acid-base equilibria (salt hydrolysis and buffer, titrations, polyprotic and amphoteric substances).

Hand, C.W.; Blewit, H.L.

1985-01-01

172

Acid Rain Lesson Plan  

NSDL National Science Digital Library

Five articulated lessons focus on air quality using classroom and field data collection activities. Case study in Great Smoky Mountains has broader application. Background and data for lessons on: the pH scale, understanding acid vs. base, collecting data, mapping relationship of weather events to acid rain. Links to NPS data on air quality, current values, atlas and reports, packaged datasets on ozone, meteorological conditions and other parameters. Also available: teacher resources; educator workshops.

173

Portable nucleic acid thermocyclers.  

PubMed

A nucleic acid thermal cycler is considered to be portable if it is under ten pounds, easily carried by one individual, and battery powered. Nucleic acid amplification includes both polymerase chain reaction (e.g. PCR, RT-PCR) and isothermal amplification (e.g. RPA, HDA, LAMP, NASBA, RCA, ICAN, SMART, SDA). There are valuable applications for portable nucleic acid thermocyclers in fields that include clinical diagnostics, biothreat detection, and veterinary testing. A system that is portable allows for the distributed detection of targets at the point of care and a reduction of the time from sample to answer. The designer of a portable nucleic acid thermocycler must carefully consider both thermal control and the detection of amplification. In addition to thermal control and detection, the designer may consider the integration of a sample preparation subsystem with the nucleic acid thermocycler. There are a variety of technologies that can achieve accurate thermal control and the detection of nucleic acid amplification. Important evaluation criteria for each technology include maturity, power requirements, cost, sensitivity, speed, and manufacturability. Ultimately the needs of a particular market will lead to user requirements that drive the decision between available technologies. PMID:24030680

Almassian, David R; Cockrell, Lisa M; Nelson, William M

2013-11-21

174

Mammalian Fatty Acid Elongases  

PubMed Central

Summary Very long chain fatty acids confer functional diversity on cells by variations in their chain length and degree of unsaturation. Microsomal fatty acid elongation represents the major pathway for determining the chain length of saturated, monounsaturated, and polyunsaturated fatty acids in cellular lipids. The overall reaction for fatty acid elongation involves four enzymes and utilizes malonyl CoA, NADPH, and fatty acyl CoA as substrates. While the fundamental pathway and its requirements have been known for many years, recent advances have revealed a family of enzymes involved in the first step of the reaction, i.e., the condensation reaction. Seven fatty acid elongase subtypes (Elovl #1–7) have been identified in the mouse, rat, and human genomes. These enzymes determine the rate of overall fatty acid elongation. Moreover, these enzymes also display differential substrate specificity, tissue distribution, and regulation, making them important regulators of cellular lipid composition as well as specific cellular functions. Herein, methods are described to measure elongase activity, analyze elongation products, and alter cellular elongase expression. PMID:19763486

Jump, Donald B.

2009-01-01

175

Reaction of caffeic acid derivatives with acidic nitrite  

Microsoft Academic Search

Caffeic derivatives were reacted with acidic nitrite at controlled pH in order to mimic the gastric juice conditions. At pH 2, whereas caffeic acid reacts exclusively on the side chain, its esters are readily nitrated. Under more acidic conditions (pH 1), caffeic acid methyl ester undergoes a dimerisation into a norlignan derivative.

Philippe Cotelle; Hervé Vezin

2001-01-01

176

Export of Acidity in Drainage Water from Acid Sulphate Soils  

Microsoft Academic Search

Disturbed acid sulphate soils are potent sources of acidity in coastal waterways. Monitoring studies of the drainage water for sites at East Trinity, Cairns and Pimpama, south-east Queensland indicate that considerable acidity is found in the drainage water from these sites. Hydrogen (H+), ferrous (Fe2+) and aluminium (Al) ions are the dominant acid cations involved. When drainage water is mixed

F. J Cook; W Hicks; E. A Gardner; G. D Carlin; D. W Froggatt

2000-01-01

177

EXPOSURE TO A P13KINASE INHIBITOR PRODUCED DYSMORPHOGENESIS IN NEURULATION-STAGED MOUSE EMBRYOS IN CULTURE  

EPA Science Inventory

The haloacetic acids (HAA) are a family of chemicals that are drinking water disinfection byproducts. We previously reported that bromo- and chloro-acetic acids alter embryonic development when mouse conceptuses are directly exposed to these xenobiotics in whole embryo culture. C...

178

RELTIVE POTENCIES OF SELECTED DIHALOACETATES AND THEIR MAJOR METABOLITES IN RODENT WHOLE EMBRYO CULTURE  

EPA Science Inventory

Relative potencies of selected dihaloacetic acids and their major metabolites in rodent whole embryo culture. S. Hunter, M. Blanton, E. Rogers RTD, NHEERL, ORD, US EPA, RTP, NC, 27711 Haloacetic acids (HAA) are produced by disinfection and present in tap water. S...

179

What is Acid Rain? Explore the Acid Lake  

NSDL National Science Digital Library

Acid rain is a type of air pollution that occurs when certain chemicals mix with water in the air. Most chemicals that cause acid rain come from the emissions from factories and cars. Acid rain looks just like 'normal' rain but when it falls, it can hurt plants and animals. For example, when acid rain falls into a lake or river, it makes that body of water more acidic. Many plants and animals cannot live in acidic water. Play this game, from Earth Day Canada's EcoKids program, to learn more about acid rain and its impact on the environment.

Canada, Earth D.

2010-01-01

180

Domoic acid epileptic disease.  

PubMed

Domoic acid epileptic disease is characterized by spontaneous recurrent seizures weeks to months after domoic acid exposure. The potential for this disease was first recognized in a human case study of temporal lobe epilepsy after the 1987 amnesic shellfish-poisoning event in Quebec, and was characterized as a chronic epileptic syndrome in California sea lions through investigation of a series of domoic acid poisoning cases between 1998 and 2006. The sea lion study provided a breadth of insight into clinical presentations, unusual behaviors, brain pathology, and epidemiology. A rat model that replicates key observations of the chronic epileptic syndrome in sea lions has been applied to identify the progression of the epileptic disease state, its relationship to behavioral manifestations, and to define the neural systems involved in these behavioral disorders. Here, we present the concept of domoic acid epileptic disease as a delayed manifestation of domoic acid poisoning and review the state of knowledge for this disease state in affected humans and sea lions. We discuss causative mechanisms and neural underpinnings of disease maturation revealed by the rat model to present the concept for olfactory origin of an epileptic disease; triggered in dendodendritic synapases of the olfactory bulb and maturing in the olfactory cortex. We conclude with updated information on populations at risk, medical diagnosis, treatment, and prognosis. PMID:24663110

Ramsdell, John S; Gulland, Frances M

2014-03-01

181

Electrochemical Determination of Lipoic Acid  

Microsoft Academic Search

Procedures for determining lipoic acid by voltammetry and coulometric titration with electrogenerated halogens using the biamperometric indication of the titration end-point were developed. Possible mechanisms of lipoic acid oxidation with electrogenerated halogens are discussed. Microgram amounts of lipoic acid were determined in model solutions with an RSD of 1–2%. The analytical range of lipoic acid found by voltammetry at a

G. K. Ziyatdinova; G. K. Budnikov; V. I. Pogorel'tsev

2004-01-01

182

Atmospheric Dust and Acid Rain  

Microsoft Academic Search

Why is acid rain still an environmental problem in Europe and North America despite antipollution reforms? The answer really is blowing in the wind: atmospheric dust. These airborne particles can help neutralize the acids falling on forests, but dust levels are unusually low these days. In the air dust particles can neutralize acid rain. What can we do about acid

Lars O. Hedin; Gene E. Likens

1996-01-01

183

Acid Catalysis in Modern Organic  

E-print Network

Acid Catalysis in Modern Organic Synthesis "Acid is one of the oldest, but the most important follows their earlier book "Lewis Acids in Organic Synthesis (2000)", and covers the new developments of university studies, in which an evil-smelling carbox- ylic acid and an alcohol were converted into a fragrant

Snyder, Scott A.

184

Ursodeoxycholic acid, 7-ketolithocholic acid, and chenodeoxycholic acid are primary bile acids of the nutria (Myocastor coypus).  

PubMed

Because ursodeoxycholic and chenodeoxycholic acids are interconverted in humans via 7-ketolithocholic acid, bile acid metabolism was studied in the nutria (Myocastor coypus), the bile of which is known to contain these three bile acids. Relative concentrations of ursodeoxycholic (37% +/- 20%), 7-ketolithocholic (33% +/- 17%), and chenodeoxycholic (17% +/- 9%) acids in gallbladder bile were unchanged by 5-20 h of complete biliary diversion (n = 7). Injection of either [14C]cholesterol, [14C]ursodeoxycholic, [14C]7-ketolithocholic acid, or a mixture of [7 beta-3H]chenodeoxycholic acid and [14C]chenodeoxycholic acid into bile fistula nutria demonstrated that all three bile acids can be synthesized hepatically from cholesterol, that they are interconverted sparingly (2%-5%) by the liver, but that 7-ketolithocholic acid is an intermediate in the hepatic transformation of chenodeoxycholic acid to ursodeoxycholic acid. An animal that had been fed antibiotics showed an unusually elevated concentration of ursodeoxycholic acid in gallbladder and hepatic bile, suggesting that bacterial transformation of ursodeoxycholic acid in the intestine may be a source of some biliary chenodeoxycholic acid and 7-ketolithocholic acid. PMID:3943698

Tint, G S; Bullock, J; Batta, A K; Shefer, S; Salen, G

1986-03-01

185

Nucleophilic reactions of sorbic acid  

Microsoft Academic Search

The conjugated dienoic acid structure of sorbic acid renders it susceptible to nucleophilic attack. Nucleophiles known to react with sorbic acid include sulphite ion and amines. These attack the molecule in position 5 and, in the cse of amines, cyclization to form substituted dihydropyridones may follow. Recent investigations show that thiols in general can also add to sorbic acid. Cysteine,

G. D. Khandelwal; B. L. Wedzicha

1990-01-01

186

DOCOSAHEXAENOIC ACID AND ARACHIDONIC ACID PREVENT ESSENTIAL FATTY ACID DEFICIENCY AND HEPATIC STEATOSIS  

PubMed Central

Objectives Essential fatty acids are important for growth, development, and physiologic function. Alpha-linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, we hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids. Methods Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, we provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis. Results Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks. Conclusion Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without alpha-linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model. PMID:22038210

Le, Hau D.; Meisel, Jonathan A.; de Meijer, Vincent E.; Fallon, Erica M.; Gura, Kathleen M.; Nose, Vania; Bistrian, Bruce R.; Puder, Mark

2012-01-01

187

Molecular Structure of Succinic acid  

NSDL National Science Digital Library

Succinic acid is an odorless and colorless crystal, triclinic or monoclinic prism with a very acid taste. Succinic acid is one of the natural acids found in broccoli, rhubarb, beets, asparagus, fresh meat extracts, sauerkraut and cheese. It is also a constituent of almost all plant and animal tissues and plays an important role in intermediary metabolism. Succinic acid is produced commercially by catalytic hydrogenation of maleic or fumaric acid or by acid hydrolysis of succinonitrile. Succinic acid is used in flavoring for food and beverages, and in the manufacture of lacquers, dyes, esters for perfumes, succinates, in photography and in foods as a sequestrant, buffer and neutralizing agent. Succinic acid has uses in certain drug compounds and in agricultural production. An interesting fact, succcinic acid has also been found in meteorites.

2004-11-11

188

Thiol modified mycolic acids.  

PubMed

Patient serum antibodies to mycolic acids have the potential to be surrogate markers of active tuberculosis (TB) when they can be distinguished from the ubiquitously present cross-reactive antibodies to cholesterol. Mycolic acids are known to interact more strongly with antibodies present in the serum of patients with active TB than in patients with latent TB or no TB. Examples of single stereoisomers of mycolic acids with chain lengths corresponding to major homologues of those present in Mycobacterium tuberculosis have now been synthesised with a sulfur substituent on the terminal position of the ?-chain; initial studies have established that one of these binds to a gold electrode surface, offering the potential to develop second generation sensors for diagnostic patient antibody detection. PMID:23603063

Balogun, Mohammed O; Huws, Enlli H; Sirhan, Muthana M; Saleh, Ahmed D; Al Dulayymi, Juma'a R; Pilcher, Lynne; Verschoor, Jan A; Baird, Mark S

2013-01-01

189

Molecular Structure of Citric Acid  

NSDL National Science Digital Library

Citric Acid was first isolated in 1734 by Carl Wilhelm Scheele. Citric acid is found in many fruits, in particular lemons, grapefruit, and oranges. Several types of bacteria and fungi are also known to produce citric acid. In fact, the fungus Aspergillus niger produces the vast majority of citric acid, which is used in almost all carbonated sodas. Additionally, citric acid is also used to clean stainless steel.

2002-08-13

190

Acid rain degradation of nylon  

Microsoft Academic Search

Acid rain, precipitation with a pH less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid

Kyllo

1984-01-01

191

Liposomal spherical nucleic acids.  

PubMed

A novel class of metal-free spherical nucleic acid nanostructures was synthesized from readily available starting components. These particles consist of 30 nm liposomal cores, composed of an FDA-approved 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid monomer. The surface of the liposomes was functionalized with DNA strands modified with a tocopherol tail that intercalates into the phospholipid layer of the liposomal core via hydrophobic interactions. The spherical nucleic acid architecture not only stabilizes these constructs but also facilitates cellular internalization and gene regulation in SKOV-3 cells. PMID:24983505

Banga, Resham J; Chernyak, Natalia; Narayan, Suguna P; Nguyen, SonBinh T; Mirkin, Chad A

2014-07-16

192

Polyvalent nucleic acid nanostructures.  

PubMed

Polyvalent oligonucleotide-nanoparticle conjugates possess several unique emergent properties, including enhanced cellular uptake, high antisense bioactivity, and nuclease resistance, which hypothetically originate from the dense packing and orientation of oligonucleotides on the surface of the nanoparticle. In this Communication, we describe a new class of polyvalent nucleic acid nanostructures (PNANs), which are comprised of only cross-linked and oriented nucleic acids. We demonstrate that these particles are capable of effecting high cellular uptake and gene regulation without the need of a cationic polymer co-carrier. The PNANs also exhibit cooperative binding behavior and nuclease resistance properties. PMID:21630678

Cutler, Joshua I; Zhang, Ke; Zheng, Dan; Auyeung, Evelyn; Prigodich, Andrew E; Mirkin, Chad A

2011-06-22

193

Polyvalent Nucleic Acid Nanostructures  

PubMed Central

Polyvalent oligonucleotide-nanoparticle conjugates possess several unique emergent properties including enhanced cellular uptake, high antisense bioactivity, and nuclease resistance, which hypothetically originate from the dense packing and orientation of oligonucleotides on the surface of the nanoparticle. In this communication, we describe a new class of polyvalent nucleic acid nanostructures (PNANs), which comprise only crosslinked and oriented nucleic acids. We demonstrate that these particles are capable of effecting high cellular uptake and gene regulation without the need of a cationic polymer co-carrier. The PNANs also exhibit cooperative binding behavior and nuclease resistance properties. PMID:21630678

Cutler, Joshua I.; Zhang, Ke; Zheng, Dan; Auyeung, Evelyn; Prigodich, Andrew E.

2011-01-01

194

The Acid-Base Titration of a Very Weak Acid: Boric Acid  

ERIC Educational Resources Information Center

A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

2012-01-01

195

[Studies on interaction of acid-treated nanotube titanic acid and amino acids].  

PubMed

Nanotube titanic acid (NTA) has distinct optical and electrical character, and has photocatalysis character. In accordance with these qualities, NTA was treated with acid so as to enhance its surface activity. Surface structures and surface groups of acid-treated NTA were characterized and analyzed by Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectrometry (FT-IR). The interaction between acid-treated NTA and amino acids was investigated. Analysis results showed that the lengths of acid-treated NTA became obviously shorter. The diameters of nanotube bundles did not change obviously with acid-treating. Meanwhile, the surface of acid-treated NTA was cross-linked with carboxyl or esterfunction. In addition, acid-treated NTA can catch amino acid residues easily, and then form close combination. PMID:20649031

Zhang, Huqin; Chen, Xuemei; Jin, Zhensheng; Liao, Guangxi; Wu, Xiaoming; Du, Jianqiang; Cao, Xiang

2010-06-01

196

Plant fatty acid hydroxylase  

DOEpatents

The present invention relates to the identification of nucleic acid sequences and constructs, and methods related thereto, and the use of these sequences and constructs to produce genetically modified plants for the purpose of altering the composition of plant oils, waxes and related compounds.

Somerville, Chris (Portola Valley, CA); van de Loo, Frank (Lexington, KY)

2000-01-01

197

ACID AEROSOL MEASUREMENT WORKSHOP  

EPA Science Inventory

This report documents the discussion and results of the U.S. EPA Acid Aerosol Measurement Workshop, conducted February 1-3, 1989, in Research Triangle Park, North Carolina. t was held in response to recommendations by the Clean Air Scientific Advisory Committee (CASAC) regarding ...

198

Deoxyribonucleic acid Genetic material  

E-print Network

salt to dissolve them) #12; Precipitate DNA (with ethanol) #12; Species identification VS. #12;Bag#12; Deoxyribonucleic acid Genetic material Chain of molecules linked together DNA contains in Protein Science Published by John Wiley & Sons, Inc. #12; Remove proteins that are bound to DNA (using

Rose, Michael R.

199

Federal Acid Rain Games  

Microsoft Academic Search

Federal environmental policy, designed to control acid rain, is shaped after the hierarchy of the system, and is controlled simultaneously by regional and central governments. Each governmental level controls one of two policy instruments: pollution abatement production and pollution tax. In a two-stage game where regional governments are Stackelberg leaders and control pollution taxes, the subgame perfect equilibrium is socially

Arthur J. Caplan; Emilson C. D. Silva

1999-01-01

200

Acid monitoring kit  

US Patent & Trademark Office Database

An acid monitoring kit is provided which is especially useful for monitoring acid rain. The kit includes a base plate having three discrete areas. One area is provided with a plurality of discrete separable bibulous pH indicator strips, each strip being impregnated with a selected acid-base indicator which is visually recognizable as at least one unique color in each such bibulous pH indicator strip when the bibulous strip is dry, and as a different color upon being wetted with water, the different color being dependent on the pH of the water. A second discrete area is provided with a plurality of color comparison reference standards in a plurality of zones, each zone being of a unique color which corresponds to the color of the water-wetted bibulous pH indictor strip, whereby comparison of the unique color of the pH indicator strip with the unique color of the reference standard provides an indication of the pH of the water. A third discrete area is also labelled to provide the requisite information for the use of such acid monitoring kit to correlate the unique color developed in the bibulous pH indicator strip to a unique color of the reference standard to provide an indication of the pH of the water.

1990-10-02

201

Plant fatty acid hydroxylase  

SciTech Connect

The present invention relates to the identification of nucleic acid sequences and constructs, and methods related to the use of these sequences and constructs to produce genetically modified plants for the purpose of altering the composition of plant oils, waxes and related compounds.

Somerville, C.; Loo, F. van de

2000-02-22

202

Alpha Hydroxy Acids  

MedlinePLUS

... skin or mucous membrane, such as the lips, bear a statement that conveys the following information: Sunburn Alert: This product contains an alpha hydroxy acid (AHA) that may increase your skin's sensitivity to the sun and particularly the possibility of sunburn. Use a ...

203

Molecular Structure of Aspartic Acid  

NSDL National Science Digital Library

Aspartate was first isolated in 1868 from legumin in plant seeds. Aspartic acid forms colorless crystals that are soluble in water and insoluble in alcohols and ethers. This is a naturally occurring nonessential amino acid that is produced in the liver from oxaloacetic acid, but is plentiful in meats and sprouting seeds. The amino acid is important in the Krebs cycle as well as the urea cycle, where it is vital in the elimination of dietary waste products. Aspartic acid is required for stamina, brain and neural health. This acid has been found to be important in the functioning of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and in the production of immunoglobin and antibody synthesis. A deficiency of aspartate will lead to fatigue and depression. Aspartic acid has many uses that include biological and clinical studies, preparation of culture media, and it also functions as a detergent, fungicide, germicide, and metal complexation.

2002-08-20

204

Uric acid inhibits placental system A amino acid uptake.  

PubMed

Hyperuricemia, a common clinical characteristic of preeclamptic pregnancies, has historically been considered a marker of reduced renal function in preeclamptic women. More recently it has been suggested that uric acid may directly contribute to pathological cell signaling events involved in disease progression as well as maternal and fetal pregnancy outcomes including fetal growth restriction. We hypothesize that the increased frequency of restricted fetal growth seen in relation to increasing uric acid concentrations in preeclamptic women is in part the result of uric acid-induced reductions in amino acid transport across the placenta. The objective of the current study was to examine the effects of uric acid on human placental System A amino acid transport using a primary placental villous explant model. Further, we examined the necessity of uric acid uptake and the role of redox signaling as a potential mechanism through which uric acid may attenuate System A activity. Placental uptake of a radiolabeled amino acid analogue, specific to the System A transporter, was reduced in a concentration-dependent fashion with increasing uric acid (0-7 mg/dL), corresponding to uric acid concentrations measured in healthy pregnant and preeclamptic women in the third trimester. Uric acid-induced reduction in System A activity was partially reversed by NADPH oxidase inhibition and completely eliminated by antioxidant treatment. This study demonstrates inhibition of placental System A amino acid transport with uric acid treatment, as a result of uric acid-induced stimulation of intracellular redox signaling cascades. These findings may be relevant to the increased frequency of fetal growth restriction observed in hyperuricemic preeclampsia. Additionally the results of this study, indicating a detrimental effect of hyperuricemia on amino acid transport in the placenta, at concentrations present in women with preeclampsia, also suggest a role for uric acid in the pathophysiology of preeclampsia. PMID:19058847

Bainbridge, S A; von Versen-Höynck, F; Roberts, J M

2009-02-01

205

Uric Acid Inhibits Placental System A Amino Acid Uptake?  

PubMed Central

Hyperuricemia, a common clinical characteristic of preeclamptic pregnancies, has historically been considered a marker of reduced renal function in preeclamptic women. More recently it has been suggested that uric acid may directly contribute to pathological cell signaling events involved in disease progression as well as maternal and fetal pregnancy outcomes including fetal growth restriction. We hypothesize that the increased frequency of restricted fetal growth seen in relation to increasing uric acid concentrations in preeclamptic women is in part the result of uric acid-induced reductions in amino acid transport across the placenta. The objective of the current study was to examine the effects of uric acid on human placental System A amino acid transport using a primary placental villous explant model. Further, we examined the necessity of uric acid uptake and the role of redox signaling as a potential mechanism through which uric acid may attenuate System A activity. Placental uptake of a radiolabeled amino acid analogue, specific to the System A transporter, was reduced in a concentration-dependent fashion with increasing uric acid (0?7 mg/dL), corresponding to uric acid concentrations measured in healthy pregnant and preeclamptic women in the third trimester. Uric acid-induced reduction in System A activity was partially reversed by NADPH oxidase inhibition and completely eliminated by antioxidant treatment. This study demonstrates inhibition of placental System A amino acid transport with uric acid treatment, as a result of uric acid-induced stimulation of intracellular redox signaling cascades. These findings may be relevant to the increased frequency of fetal growth restriction observed in hyperuricemic preeclampsia. Additionally the results of this study, indicating a detrimental effect of hyperuricemia on amino acid transport in the placenta, at concentrations present in women with preeclampsia, also suggest a role for uric acid in the pathophysiology of preeclampsia. PMID:19058847

Bainbridge, S.A.; von Versen-Hoynck, F.; Roberts, J.M.

2009-01-01

206

Specific bile acids inhibit hepatic fatty acid uptake  

PubMed Central

Bile acids are known to play important roles as detergents in the absorption of hydrophobic nutrients and as signaling molecules in the regulation of metabolism. Here we tested the novel hypothesis that naturally occurring bile acids interfere with protein-mediated hepatic long chain free fatty acid (LCFA) uptake. To this end stable cell lines expressing fatty acid transporters as well as primary hepatocytes from mouse and human livers were incubated with primary and secondary bile acids to determine their effects on LCFA uptake rates. We identified ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA) as the two most potent inhibitors of the liver-specific fatty acid transport protein 5 (FATP5). Both UDCA and DCA were able to inhibit LCFA uptake by primary hepatocytes in a FATP5-dependent manner. Subsequently, mice were treated with these secondary bile acids in vivo to assess their ability to inhibit diet-induced hepatic triglyceride accumulation. Administration of DCA in vivo via injection or as part of a high-fat diet significantly inhibited hepatic fatty acid uptake and reduced liver triglycerides by more than 50%. In summary, the data demonstrate a novel role for specific bile acids, and the secondary bile acid DCA in particular, in the regulation of hepatic LCFA uptake. The results illuminate a previously unappreciated means by which specific bile acids, such as UDCA and DCA, can impact hepatic triglyceride metabolism and may lead to novel approaches to combat obesity-associated fatty liver disease. PMID:22531947

Nie, Biao; Park, Hyo Min; Kazantzis, Melissa; Lin, Min; Henkin, Amy; Ng, Stephanie; Song, Sujin; Chen, Yuli; Tran, Heather; Lai, Robin; Her, Chris; Maher, Jacquelyn J.; Forman, Barry M.; Stahl, Andreas

2012-01-01

207

Fatty acid-producing hosts  

SciTech Connect

Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

Pfleger, Brian F; Lennen, Rebecca M

2013-12-31

208

Acidizing of Sandstone Reservoirs Using HF and Organic Acids  

E-print Network

Mud acid, which is composed of HCl and HF, is commonly used to remove the formation damage in sandstone reservoirs. However, many problems are associated with HCl, especially at high temperatures. Formic-HF acids have served as an alternative...

Yang, Fei

2012-10-19

209

Thiobarbituric Acid Spray Reagent for Deoxy Sugars and Sialic Acids  

Microsoft Academic Search

RECENTLY, new sensitive assays have been reported for deoxy sugars1, 2-keto,3-deoxy sugar acids2-4, and sialic acids5,6. In these assays, the products of periodate oxidation, malonaldehyde from deoxy sugars and beta-formylpyruvic acid from the latter two groups of compounds, are coupled with 2-thiobarbituric acid to produce a bright red chromophore. I wish to report an adaptation of these methods for spraying

Leonard Warren

1960-01-01

210

Preterm infant formula supplementation with ? linolenic acid and docosahexaenoic acid  

Microsoft Academic Search

Objectives: To investigate if supplementation of preterm infant formula with a high docosahexaenoic acid\\/eicosapentaenoic acid (DHA\\/EPA) ratio together with ?-linolenic acid (ALA) was able to maintain plasma and red blood cell DHA levels similar to that obtained with breast milk feeding without altering n-6 fatty acid status.Design and subjects: Preterm infants of mothers who elected not to breast feed (n=13)

A Rodriguez; D Raederstorff; P Sarda; C Lauret; F Mendy; B Descomps

2003-01-01

211

Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN  

E-print Network

Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN A. Solubility Tests: Water, NaHCO3, and NaOH Test the solubility of your acid first in neutral water, in NaOH/H2O, and in NaHCO3 to 30 drops. Swirl/mix well. Use of small stir bar helps. · Water Test: Only acids with small numbers

Jasperse, Craig P.

212

Boswellic acid inhibits expression of acid sphingomyelinase in intestinal cells  

PubMed Central

Background Boswellic acid is a type of triterpenoids with antiinflammatory and antiproliferative properties. Sphingomyelin metabolism generates multiple lipid signals affecting cell proliferation, inflammation, and apoptosis. Upregulation of acid sphingomyelinase (SMase) has been found in several inflammation-related diseases such as inflammatory bowel diseases, atherosclerosis, and diabetes. Methods The present study is to examine the effect of 3-acetyl-11-keto-?-boswellic acids (AKBA), a potent boswellic acid, on acid SMase activity and expression in intestinal cells. Both transformed Caco-2 cells and non-transformed Int407 cells were incubated with AKBA. After incubation, the change of acid SMase activity was assayed biochemically, the enzyme protein was examined by Western blot, and acid SMase mRNA was quantified by qPCR. Results We found that AKBA decreased acid SMase activity in both intestinal cell lines in dose and time dependent manners without affecting the secretion of the enzyme to the cell culture medium. The effect of AKBA was more effective in the fetal bovine serum-free culture medium. Among different types of boswellic acid, AKBA was the most potent one. The inhibitory effect on acid SMase activity occurred only in the intact cells but not in cell-free extract in the test tubes. At low concentration, AKBA only decreased the acid SMase activity but not the quantity of the enzyme protein. However, at high concentration, AKBA decreased both the mass of acid SMase protein and the mRNA levels of acid SMase in the cells, as demonstrated by Western blot and qPCR, respectively. Under the concentrations decreasing acid SMase activity, AKBA significantly inhibited cell proliferation. Conclusion We identified a novel inhibitory effect of boswellic acids on acid SMase expression, which may have implications in human diseases and health. PMID:19951413

2009-01-01

213

Acid Earth--The Global Threat of Acid Pollution.  

ERIC Educational Resources Information Center

Acid pollution is a major international problem, but the debate it has elicited has often clouded the distinction between myth and facts. This publication attempts to concerning the acid pollution situation. This publication attempts to identify available facts. It is the first global review of the problem of acid pollution and the first to…

McCormick, John

214

Focus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid  

E-print Network

characterized by weight loss, brittle bones, anemia, and general ill health. Safe use If possible, avoid workingFocus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid Hydrofluoric acid (HF bone. Skin exposure to highly concentrated HF (48% or greater) immediately results in serious

Wilcock, William

215

Acid placement and coverage in the acid jetting process  

E-print Network

Many open-hole acid treatments are being conducted by pumping acid through jetting ports placed at the end of coiled tubing or drill pipe. The filter-cake on the bore-hole is broken by the jet; the acid-soluble material is dissolved, creating...

Mikhailov, Miroslav I.

2009-05-15

216

Autohydrolysis of phytic acid.  

PubMed

The autohydrolysis of phytic acid at 120 degrees C resulted in the formation of most of the phosphate esters of myo-inositol in varying amounts depending upon the reaction time. Eighteen of the 39 chromatographically distinct myo-inositol mono-, bis-, tris-, tetrakis-, pentakis-, and hexakisphosphates have been characterized using two different HPLC systems. These myo-inositol phosphates were partially purified by preparative anion-exchange chromatography under acidic and alkaline elution conditions. The combination of these two methods provides a two-tiered chromatographic approach to the rapid and sensitive identification of inositol phosphates in complex mixtures. Identification of the products was confirmed by 1D and 2D (1)H NMR analysis. The analytical procedure was applied to the autohydrolysis of the mixture of inositol phosphates from corn steep water. PMID:10469496

Hull, S R; Gray, J S; Montgomery, R

1999-09-10

217

Acid hydrolysis of cellulose  

SciTech Connect

One of the alternatives to increase world production of etha nol is by the hydrolysis of cellulose content of agricultural residues. Studies have been made on the types of hydrolysis: enzimatic and acid. Data obtained from the sulphuric acid hydrolysis of cellulose showed that this process proceed in two steps, with a yield of approximately 95% glucose. Because of increases in cost of alternatives resources, the high demand of the product and the more economic production of ethanol from cellulose materials, it is certain that this technology will be implemented in the future. At the same time further studies on the disposal and reuse of the by-products of this production must be undertaken.

Salazar, H.

1980-12-01

218

(Radioiodinated free fatty acids)  

SciTech Connect

The traveler participated in the Second International Workshop on Radioiodinated Free Fatty Acids in Amsterdam, The Netherlands where he presented an invited paper describing the pioneering work at the Oak Ridge National Laboratory (ORNL) involving the design, development and testing of new radioiodinated methyl-branched fatty acids for evaluation of heart disease. He also chaired a technical session on the testing of new agents in various in vitro and in vivo systems. He also visited the Institute for Clinical and Experimental Nuclear Medicine in Bonn, West Germany, to review, discuss, plan and coordinate collaborative investigations with that institution. In addition, he visited the Cyclotron Research Center in Liege, Belgium, to discuss continuing collaborative studies with the Osmium-191/Iridium-191m radionuclide generator system, and to complete manuscripts and plan future studies.

Knapp, Jr., F. F.

1987-12-11

219

The utilization of tricarboxylic acid cycle acids and the uptake of succinic acid by Neurospora crassa  

E-print Network

, Clavice s u urea and several species of ~dtlt . 1' ~ d 9' p ~ d t 1966 (69) th t ~C. PRL 1980 was able to grow with succinic acid as the sole carbon source in an acidic medium. The efficiency of total biomass synthesis on succinic acid was considerably..., Clavice s u urea and several species of ~dtlt . 1' ~ d 9' p ~ d t 1966 (69) th t ~C. PRL 1980 was able to grow with succinic acid as the sole carbon source in an acidic medium. The efficiency of total biomass synthesis on succinic acid was considerably...

Gilliland, Patti Lynn

2012-06-07

220

Molecular Structure of Sulfuric Acid  

NSDL National Science Digital Library

H2SO4 was discovered by alchemists and made from heating a compound of iron sulfate. In 1740, sulfuric acid was produced for commercial sale. Sulfuric acid is a very strong acid which is used in car batteries. The acid disassociates in water to give two protons and sulfate. This acid can destroy flesh and cause blindness. It was discovered in the 19th century that adding sulfuric acid to soil produces phosphorus, which is beneficial to plants; hence, sulfuric acid is used as a fertilizer in the form of super phosphate and ammonium sulfate. Sulfuric acid is also used to refine petroleum and process metals, and is found in paints and car batteries.

2002-08-15

221

Molecular Structure of Maleic acid  

NSDL National Science Digital Library

Maleic acid is colorless to white crystals with a faint acidulous odor and a characteristic repulsive, astringent taste. Maleic acid is used in making polyesters, surface coatings, lubricant additives, agricultural chemicals and paint vehicles. It is used in organic synthesis of fumaric acid, succinic, aspartic, tartaric, propionic, lactic, malonic, acrylic and hydrocarylic acids. Maleic acid and its anhydride are prepared industrially by the catalytic oxidation of benzene. Maleic acid may be released into waste water during its production and used in the manufacture of polymer products. Dust of maleic acid is irritating to the eyes, nose and throat. The general population is exposed to maleic acid in areas with heavy traffic since it is found in aerosols from auto exhaust.

2004-11-10

222

Crosslinked acid gels offer advantages  

SciTech Connect

Acid polymer gels having a pH less than one have been crosslinked for retarding the chemical and physical activity of hydrochloric acid on calcareous formations. Hydrochloric acid concentrations from /one quarter/% to 28% have been successfully crosslinked. This unique stimulation fluid offers high viscosity with adequate shear stability, perfect support for propants, and clay stabilization. Additionally, the fluid provided effective fluid loss control and retardation of acid reaction enabling live acid to penetrate deeper into the formation for better conductivity; furthermore, there is practically a residue free break for rapid cleanup of the well after the job. Results of lab and field tests show this new acid crosslinked system to be an effective stimulation fluid for acidizing and acid fracturing in calcareous and sandstone formations having low permeability. 5 refs.

Pabley, A.S.; Holcomb, D.L.

1981-09-28

223

Molecular Structure of Glutaric acid  

NSDL National Science Digital Library

Glutaric acid is a colorless liquid and white crystals as a solid occurring in plants and animal tissues. It is used in organic synthesis and as an intermediate for the manufacture of polymers such as polyamides and polyesters, ester plasticizers and corrosion inhibitors. It is also useful in the application of decreasing polymer elasticity and in a variety of industrial applications. In addition glutaric acid plays an important role as an intermediary in the Krebs cycle and is used in medication against a large number of viruses and in animal diabetes. Glutaric acid can be prepared from cyclopentanone by oxidative ring fission with nitric acid and in the presence of a catalyst. Glutaric acid has the lowest melting point among dicarboxylic acids (98 C); it is very soluble in water and the solution in water is a medium strong acid. Short-term exposure to glutaric acid may cause irritation to the eyes, skin and the respiratory tract.

2004-11-10

224

Acid hydrolysis of chitosans  

Microsoft Academic Search

The hydrolysis of the O-glycosidic linkages (depolymerization) and the N-acetyl linkage (de-N-acetylation) of partially N-acetylated chitosans were studied in dilute and concentrated HCl. The rate of hydrolysis of the glycosidic linkages was found to be equal to the rate of de-N-acetylation in dilute acid, while the glycosidic linkages was hydrolysed more than 10 times faster than the N-acetyl linkage in

K. M. Vårum; M. H. Ottøy; O. Smidsrød

2001-01-01

225

Acid rain in Asia  

Microsoft Academic Search

Acid rain has been an issue of great concern in North America and Europe during the past several decades. However, due to\\u000a the passage of a number of recent regulations, most notably the Clean Air Act in the United States in 1990, there is an emerging\\u000a perception that the problem in these Western nations is nearing solution. The situation in

Neeloo Bhatti; David G. Streets; Wesley K. Foell

1992-01-01

226

Lipoic acid biosynthesis defects.  

PubMed

Lipoate is a covalently bound cofactor essential for five redox reactions in humans: in four 2-oxoacid dehydrogenases and the glycine cleavage system (GCS). Two enzymes are from the energy metabolism, ?-ketoglutarate dehydrogenase and pyruvate dehydrogenase; and three are from the amino acid metabolism, branched-chain ketoacid dehydrogenase, 2-oxoadipate dehydrogenase, and the GCS. All these enzymes consist of multiple subunits and share a similar architecture. Lipoate synthesis in mitochondria involves mitochondrial fatty acid synthesis up to octanoyl-acyl-carrier protein; and three lipoate-specific steps, including octanoic acid transfer to glycine cleavage H protein by lipoyl(octanoyl) transferase 2 (putative) (LIPT2), lipoate synthesis by lipoic acid synthetase (LIAS), and lipoate transfer by lipoyltransferase 1 (LIPT1), which is necessary to lipoylate the E2 subunits of the 2-oxoacid dehydrogenases. The reduced form dihydrolipoate is reactivated by dihydrolipoyl dehydrogenase (DLD). Mutations in LIAS have been identified that result in a variant form of nonketotic hyperglycinemia with early-onset convulsions combined with a defect in mitochondrial energy metabolism with encephalopathy and cardiomyopathy. LIPT1 deficiency spares the GCS, and resulted in a combined 2-oxoacid dehydrogenase deficiency and early death in one patient and in a less severely affected individual with a Leigh-like phenotype. As LIAS is an iron-sulphur-cluster-dependent enzyme, a number of recently identified defects in mitochondrial iron-sulphur cluster synthesis, including NFU1, BOLA3, IBA57, GLRX5 presented with deficiency of LIAS and a LIAS-like phenotype. As in DLD deficiency, a broader clinical spectrum can be anticipated for lipoate synthesis defects depending on which of the affected enzymes is most rate limiting. PMID:24777537

Mayr, Johannes A; Feichtinger, René G; Tort, Frederic; Ribes, Antonia; Sperl, Wolfgang

2014-07-01

227

Acid Deposition Sampling  

NSDL National Science Digital Library

This learning activity from the Advanced Technology Environmental and Energy Center (ATEEC) provides students with the opportunity to use analytical meters and instruments and perform acid deposition sampling. Students will collect samples from various sources over a period of time, then measure pH and develop graphs or charts. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

Willey, Babe

2011-02-17

228

Modulation of membrane curvature by phosphatidic acid and lysophosphatidic acid.  

PubMed

The local generation of phosphatidic acid plays a key role in the regulation of intracellular membrane transport through mechanisms which are largely unknown. Phosphatidic acid may recruit and activate downstream effectors, or change the biophysical properties of the membrane and directly induce membrane bending and/or destabilization. To evaluate these possibilities, we determined the phase properties of phosphatidic acid and lysophosphatidic acid at physiological conditions of pH and ion concentrations. In single-lipid systems, unsaturated phosphatidic acid behaved as a cylindrical, bilayer-preferring lipid at cytosolic conditions (37 degrees C, pH 7.2, 0.5 mM free Mg2+), but acquired a type-II shape at typical intra-Golgi conditions, a mildly acidic pH and submillimolar free Ca2+ (pH 6.6-5.9, 0.3 mM Ca2+). Lysophosphatidic acid formed type-I lipid micelles in the absence of divalent cations, but anhydrous cation-lysophosphatidic acid bilayer complexes in their presence. These data suggest a similar molecular shape for phosphatidic acid and lysophosphatidic acid at cytosolic conditions; however, experiments in mixed-lipid systems indicate that their shape is not identical. Lysophosphatidic acid stabilized the bilayer phase of unsaturated phosphatidylethanolamine, while the opposite effect was observed in the presence of phosphatidic acid. These results support the hypothesis that a conversion of lysophosphatidic acid into phosphatidic acid by endophilin or BARS (50 kDa brefeldin A ribosylated substrate) may induce negative spontaneous monolayer curvature and regulate endocytic and Golgi membrane fission. Alternative models for the regulation of membrane fission based on the strong dependence of the molecular shape of (lyso)phosphatidic acid on pH and divalent cations are also discussed. PMID:12656989

Kooijman, Edgar E; Chupin, Vladimir; de Kruijff, Ben; Burger, Koert N J

2003-03-01

229

Exposures to acidic aerosols  

SciTech Connect

Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m/sup 3/ more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m/sup 3/ (approximately 27 micrograms/m/sup 3/ H/sub 2/SO/sub 4/). The maximum estimated 1-hr concentration exceeded 1500 nmole/m/sup 3/ for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H/sub 2/SO/sub 4/ exceeded 50 micrograms/m/sup 3/.

Spengler, J.D.; Keeler, G.J.; Koutrakis, P.; Ryan, P.B.; Raizenne, M.; Franklin, C.A.

1989-02-01

230

Exposures to acidic aerosols  

SciTech Connect

Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H(+) ion concentrations exceeding 100 nmole/cu m more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H(+) determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr (H+) concentrations exceeded 550 nmole/cu m (approximately 27 microgram/cu m H{sub 2}SO{sub 4}). The maximum estimated 1-hr concentration exceeded 1500 nmole/cu m for H(+) ions. At these concentrations, an active child might receive more than 2000 nmole of H(+) ion in 12 hr and in excess of 900 nmole during the hour when H{sub 2}SO{sub 4} exceeded 50 microgram/cu m.

Spengler, J.D.; Keeler, G.J.; Koutrakis, P.; Ryan, P.B.; Raizenne, M.

1989-01-01

231

Grading acid rain research  

NASA Astrophysics Data System (ADS)

The growing concern with the environmental effects of acid rain has spawned a number of study groups in recent years, and now the Office of Science and Technology Policy (OSTP) has released what is essentially a study of a study. In January 1982, White House Science Advisor George Keyworth asked William Nierenberg, Director of the Scripps Institution of Oceanography, and a panel of nine scientists to conduct a peer review of three separate reports on acid deposition in eastern North America that had been turned in by U.S.-Canadian scientific working groups.Those studies had been requisitioned by a 1980 Memorandum of Intent between the United States and Canada regarding transboundary air pollution. Overall, the Nierenberg peer review panel was “impressed with the efforts of the United States-Canadian Working Groups,” (labeled Groups 1, 2, and 3B), but it also found problems. While applauding the work groups' exhaustive search through the acid rain literature, the Nierenberg panel cited what they call an “overdependence on ‘soft’ literature,” or writings such as in-house reports and personal communications, which are outside the publicly available (and carefully scrutinized) body of scientific literature.

232

Microbial naphthenic Acid degradation.  

PubMed

Naphthenic acids (NAs) are an important group of trace organic pollutants predominantly comprising saturated aliphatic and alicyclic carboxylic acids. NAs are ubiquitous; occurring naturally in hydrocarbon deposits (petroleum, oil sands, bitumen, and crude oils) and also have widespread industrial uses. Consequently, NAs can enter the environment from both natural and anthropogenic processes. NAs are highly toxic, recalcitrant compounds that persist in the environment for many years, and it is important to develop efficient bioremediation strategies to decrease both their abundance and toxicity in the environment. However, the diversity of microbial communities involved in NA-degradation, and the mechanisms by which NAs are biodegraded, are poorly understood. This lack of knowledge is mainly due to the difficulties in identifying and purifying individual carboxylic acid compounds from complex NA mixtures found in the environment, for microbial biodegradation studies. This paper will present an overview of NAs, their origin and fate in the environment, and their toxicity to the biota. The review describes the microbial degradation of both naturally occurring and chemically synthesized NAs. Proposed pathways for aerobic NA biodegradation, factors affecting NA biodegradation rates, and possible bioremediation strategies are also discussed. PMID:20359455

Whitby, Corinne

2010-01-01

233

Acid rain: Reign of controversy  

SciTech Connect

Acid Rain is a primer on the science and politics of acid rain. Several introductory chapters describe in simple terms the relevant principles of water chemistry, soil chemistry, and plant physiology and discuss the demonstrated or postulated effects of acid rain on fresh waters and forests as well as on statuary and other exposed objects. There follow discussions on the economic and social implications of acid rain (for example, possible health effects) and on the sources, transport, and distribution of air pollutants.

Kahan, A.M.

1986-01-01

234

Enviropedia: Introduction to Acid Rain  

NSDL National Science Digital Library

This resource provides information about acid rain, a widespread term used to describe all forms of acid precipitation. The sources, nature, and chemistry of acid rain are discussed, along with its impact on buildings, soils, freshwater lakes, trees, and wildlife. Other topics include measuring, modeling, and monitoring acid rain; and vehicle and industrial emission controls. The problem of airborne pollutants migrating across international borders is also discussed.

235

Antioxidant properties of nitrocaffeic acids  

Microsoft Academic Search

A series of nitrodihydroxybenzenes and nitrocaffeic acids were prepared and their hydroxyl radical (OH°) and superoxide anion (O2?) scavenging activities and xanthine oxidase inhibition activities were evaluated. 2-Nitrocaffeic acid is the more potent O2? scavenger. 2- (and 5)-Nitrocaffeic acids are the more potent xanthine oxidase inhibitors.

Jean-Luc Grenier; Nicole Cotelle; Philippe Cotelle; Jean-Pierre Catteau

1996-01-01

236

Acid rain and dry deposition  

Microsoft Academic Search

This book provides information on the formation of acid rain and the long-range transport of air pollutants. The effects of acid precipitation on both terrestrial and aquatic ecosystems are highlighted and technical and policy issues associated with the delineation and implementation of control strategies for acid rain and dry deposition are covered. Dry deposition is addressed, with emphasis given to

Canter

1985-01-01

237

Acid rain: the international response  

Microsoft Academic Search

Acid rain or technically “acid deposition” has far reaching environmental, economic, political and international implications. It has been blamed for large?scale damage to aquatic ecosystems and forests in Scandinavia, southeastern Canada and the northeastern United States. A number of other countries have expressed concern about the possible affects of acid rain on water bodies, forests, agricultural crops and material structures.Never

Gordon L. Brady; Joseph C. Selle

1985-01-01

238

Carboxylic acid sorption regeneration process  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine.

King, C. Judson (Kensington, CA); Poole, Loree J. (Baton Rouge, LA)

1995-01-01

239

Do We Need Gastric Acid?  

Microsoft Academic Search

Evidence from comparative anatomy and physiology studies indicates that gastric acid secretion developed during the evolution of vertebrates approximately 350 million years ago. The cellular mechanisms that produce gastric acid have been conserved over the millennia and therefore proton pump inhibitors have pharmacological effects in almost all relevant species. These observations suggest that gastric acid provides an important selective advantage;

D. Pohl; M. Fox; M. Fried; B. Göke; C. Prinz; H. Mönnikes; G. Rogler; M. Dauer; J. Keller; F. Lippl; I. Schiefke; U. Seidler; H. D. Allescher

2008-01-01

240

Carboxylic acid sorption regeneration process  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine. 10 figs.

King, C.J.; Poole, L.J.

1995-05-02

241

Determination of the solubility products of nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid  

Microsoft Academic Search

A method is described for the determination of solubility products for polyaminopolycarboxylic acids. The neutral protonated species of NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid) were precipitated at low pH values. The amount of precipitate was quantified by gravimetry and complexometric titrations with a standard zinc(II) solution. The following solubility products were obtained: SH3NTA=10?16.36, SH4EDTA=10?24.66 and SH5DTPA=10?30.43.

Jouni Karhu; Leo Harju; Ari Ivaska

1999-01-01

242

Solvent extraction of inorganic acids  

E-print Network

and solubility of nitric acid and sulfuric acid with organic solvents have been published Olander, Donadieu, and Benedict (12) studied the 'istributlon of nitric acid between water and tributyl phosphate-hexane solvent nd dcharf and Gean. . oplis (1...(. ) reported on the system nit ic acid-water-n-butyl alcohols Distribution of sulfuric acid was m-de oy Bchlea and Gean- koplis (19) with n-butyl alcohol, by Gibby ( 7) with nitro- benzene and by Peakin (14) with pyri 'in~. Baldwin, Biggies an" Soldano (2...

Ysrael, Miguel Curie

2012-06-07

243

The politics of acid rain  

SciTech Connect

This work examines and compares the acid rain policies through the different political systems of Canada, Great Britain and the United States. Because the flow of acid rain can transcend national boundaries, acid rain has become a crucial international problem. According to the author, because of differences in governmental institutions and structure, the extent of governmental intervention in the industrial economy, the degree of reliance on coal for power generation, and the extent of acid rain damage, national responses to the acid rain problem have varied.

Wilcher, M.E. (Pennsylvania State Univ., New Kensington, PA (US))

1989-01-01

244

Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.  

ERIC Educational Resources Information Center

Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

Raw, C. J. G.; And Others

1983-01-01

245

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids to quantify compounds at fmol m-3 levels. Mean total FAA concentration was 1070 fmol m-3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45-60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m-3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (<0.49 ?m) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanics.

Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

2012-07-01

246

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids and quantify compounds at fmol m-3 levels. Mean total FAA concentration was 1070 fmol m-3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45-60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m-3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (< 0.49 ?m) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanic emissions.

Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

2012-11-01

247

Molecular Structure of Picric acid  

NSDL National Science Digital Library

Picric Acid was first discovered in 1771 by a British Chemist named Peter Woulfe by treatment of indigo with nitric acid. It is most commonly seen in its yellow, water-soluble, crystalline form. For this reason, picric acid first saw use as a dyeing agent in textiles. However, around 1849 it was discovered (for obvious reasons) that picric acid is a shock, heat, and friction-sensitive explosive. Its first use as an explosive material came in military weaponry: torpedoes in particular due to its shock-sensitive nature not requiring a detonator to explode on contact with a target. However, picric acid was found to be highly corrosive to metals, making the weapons very difficult to handle and the acid itself difficult to store. Today, picric acid is used more widely as an ingredient in the manufacture of inert dyes and stable explosives such as dynamite.

2002-09-23

248

Molecular Structure of Sorbic acid  

NSDL National Science Digital Library

Sorbic acid is a colorless or white crystalline powder, with a weak characteristic odor and slightly acidic taste. It may be obtained from berries of the mountain ash or prepared synthetically by condensing crotonaldehyde and malonic acid in pyridine solution. Sorbic acid is a polyunsaturated fat used to inhibit molds and yeast, is a fungistatic agent for foods (especially cheeses, wine and baked goods). The main use of sorbic acid is as a preservative in foods, animal feeds, tobacco, cosmetics and pharmaceuticals, as well in packing materials for these substances and in other products that come in contact with human or animal skin in some way. Sorbic acid is also used as an intermediate for plasticizers and lubricants. Sorbic acid reacts with potassium to make potassium sorbate and with calcium to make calcium sorbate.

2004-11-11

249

Formation of disinfection by-products in indoor swimming pool water: The contribution from filling water natural organic matter and swimmer body fluids  

Microsoft Academic Search

The contribution and role of different precursors in the formation of three class of disinfection by-products (DBPs) [trihalomethanes (THMs), haloacetic acids (HAAs), and halonitromethanes (HNMs)] in swimming pool waters were examined using filling waters obtained from five drinking water treatment plant (WTP) effluents and three body fluid analogs (BFAs). BFAs exerted higher chlorine demands as compared to natural organic matter

Amer Kanan; Tanju Karanfil

2011-01-01

250

COAGULATION  

EPA Science Inventory

This chapter reports on the efforts of the USEPA to study conventional and enhanced coagulation for the control of disinfection by-products (DBPs) in drinking water. It examines the control of DBPs like trihalomethanes, haloacetic acids and the surrogate total organic halide in t...

251

DBP FORMATION KINETICS IN A SIMULATED DISTRIBUTION SYSTEM  

EPA Science Inventory

Little is known about how the growth of halogenated disinfection by-products (DBPs) in drinking water is affected by time spent in a distribution system. Experiments were performed to compare the rate of trihalomethane and haloacetic acid production in a simulated pipe environmen...

252

Characterization of natural organic matter in conventional water treatment processes for selection of treatment processes focused on DBPs control  

Microsoft Academic Search

Natural organic matter (NOM) from raw and process waters at a conventional water treatment plant was isolated into hydrophobic and hydrophilic fractions by physicochemical fractionation methods to investigate its characteristics. Formation potential of trihalomethanes (THMs) was highly influenced by the hydrophobic fraction, whereas haloacetic acids formation potential (HAAFP) depended more on the hydrophilic fraction. However the hydrophobic fraction was removed

Hyun-Chul Kim; Myong-Jin Yu

2005-01-01

253

Biochemical composition of organic matter in UK Midlands catchments: implications for drinking water treatment  

Microsoft Academic Search

Insufficient removal of natural organic matter at treatment works can lead to the formation of potentially carcinogenic disinfection by-products (mainly trihalomethanes and haloacetic acids, THMs and HAAs) due to reactions of residual organic matter with chlorine added at the disinfection stage of water treatment process. However, the total organic carbon (TOC) removal efficiency is controlled by the content and character

M. Bieroza; J. Bridgeman; A. Baker

2007-01-01

254

Analytical methods for water disinfection byproducts in foods and beverages  

Microsoft Academic Search

The determination of exposure to drinking water disinfection byproducts (DBPs) requires an understanding of how drinking water comes into contact with human through multiple pathways. In order to facilitate the investigation of human exposure to DBPs via foods and beverages, analytical method development efforts were initiated for haloacetonitriles, haloketones, chloropicrin, and the haloacetic acids (HAAs) in these matrices. The recoveries

JAMES H RAYMER; EDO PELLIZZARI; BRENDA CHILDS; KEITH BRIGGS; JODY A SHOEMAKER

2000-01-01

255

Corals on Acid  

NSDL National Science Digital Library

The objective of this inquiry-based lesson is for learners to gain an understanding of how increasing ocean acidity can affect the calcification of marine organisms. During this activity, learners: (1) design an experiment to quantify the CaCO3 concentration of two invertebrate skeletal samples, one that has been soaked in normal seawater and another in a low pH solution, and (2) use critical thinking and discussion to evaluate possible explanations for the difference in the skeletal CaCO3 compositions. This lesson plan includes a post-activity demonstration, which shows how the dissolution of CO2 into the ocean lowers pH.

Boleman, Casey L.; Gravinese, Philip M.; Muse, Ellen N.; Marston, Andrea E.; Windsor, John G.

2013-01-01

256

Microbial hyaluronic acid production.  

PubMed

Hyaluronic acid (HA) is a commercially valuable medical biopolymer increasingly produced through microbial fermentation. Viscosity limits product yield and the focus of research and development has been on improving the key quality parameters, purity and molecular weight. Traditional strain and process optimisation has yielded significant improvements, but appears to have reached a limit. Metabolic engineering is providing new opportunities and HA produced in a heterologous host is about to enter the market. In order to realise the full potential of metabolic engineering, however, greater understanding of the mechanisms underlying chain termination is required. PMID:15599518

Chong, Barrie Fong; Blank, Lars M; Mclaughlin, Richard; Nielsen, Lars K

2005-01-01

257

Action of picolinic acid and structurally related pyridine carboxylic acids on quinolinic acid-induced cortical cholinergic damage  

Microsoft Academic Search

Picolinic acid, a pyridine monocarboxylic acid derived from tryptophan metabolism by the kynurenine pathway, was shown to block cortical cholinergic neurotoxicity induced by quinolinic acid (QUIN), a pyridine dicarboxylic acid yielded by the same pathway. This study examined the specificity of the anti-toxic effect of picolinic acid by comparing its effect with several structurally related mono- and dicarboxylic acids, and

J. Cockhill; K. Jhamandas; R. J. Boegman; R. J. Beninger

1992-01-01

258

Solid-phase extraction of acidic herbicides.  

PubMed

A discussion of solid-phase extraction method development for acidic herbicides is presented that reviews sample matrix modification, extraction sorbent selection, derivatization procedures for gas chromatographic analysis, and clean-up procedures for high-performance liquid chromatographic analysis. Acidic herbicides are families of compounds that include derivatives of phenol (dinoseb, dinoterb and pentachlorophenol), benzoic acid (acifluorfen, chloramben, dicamba, 3,5-dichlorobenzoic acid and dacthal--a dibenzoic acid derivative), acetic acid [2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)], propanoic acid [dichlorprop, fluazifop, haloxyfop, 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and silvex], butanoic acid [4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB) and 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB)], and other miscellaneous acids such as pyridinecarboxylic acid (picloram) and thiadiazine dioxide (bentazon). PMID:10941675

Wells, M J; Yu, L Z

2000-07-14

259

Nucleic Acid Detection Methods  

DOEpatents

The invention relates to methods for rapidly determining the sequence and/or length a target sequence. The target sequence may be a series of known or unknown repeat sequences which are hybridized to an array of probes. The hybridized array is digested with a single-strand nuclease and free 3'-hydroxyl groups extended with a nucleic acid polymerase. Nuclease cleaved heteroduplexes can be easily distinguish from nuclease uncleaved heteroduplexes by differential labeling. Probes and target can be differentially labeled with detectable labels. Matched target can be detected by cleaving resulting loops from the hybridized target and creating free 3-hydroxyl groups. These groups are recognized and extended by polymerases added into the reaction system which also adds or releases one label into solution. Analysis of the resulting products using either solid phase or solution. These methods can be used to detect characteristic nucleic acid sequences, to determine target sequence and to screen for genetic defects and disorders. Assays can be conducted on solid surfaces allowing for multiple reactions to be conducted in parallel and, if desired, automated.

Smith, Cassandra L. (Boston, MA); Yaar, Ron (Brookline, MA); Szafranski, Przemyslaw (Boston, MA); Cantor, Charles R. (Boston, MA)

1998-05-19

260

Nucleic acid detection methods  

DOEpatents

The invention relates to methods for rapidly determining the sequence and/or length a target sequence. The target sequence may be a series of known or unknown repeat sequences which are hybridized to an array of probes. The hybridized array is digested with a single-strand nuclease and free 3{prime}-hydroxyl groups extended with a nucleic acid polymerase. Nuclease cleaved heteroduplexes can be easily distinguish from nuclease uncleaved heteroduplexes by differential labeling. Probes and target can be differentially labeled with detectable labels. Matched target can be detected by cleaving resulting loops from the hybridized target and creating free 3-hydroxyl groups. These groups are recognized and extended by polymerases added into the reaction system which also adds or releases one label into solution. Analysis of the resulting products using either solid phase or solution. These methods can be used to detect characteristic nucleic acid sequences, to determine target sequence and to screen for genetic defects and disorders. Assays can be conducted on solid surfaces allowing for multiple reactions to be conducted in parallel and, if desired, automated. 18 figs.

Smith, C.L.; Yaar, R.; Szafranski, P.; Cantor, C.R.

1998-05-19

261

Growth of nitric acid hydrates on thin sulfuric acid films  

NASA Technical Reports Server (NTRS)

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

1994-01-01

262

Sedimentation of sulfuric acid in acid tars from current production  

Microsoft Academic Search

Acid tars obtained in treating T-750, KhF-12, and I-8A oils were investigated for purposes of recovering sulfuric acid and asphalt binders from the compositions and of determining the effects of storage time on the recovery. The consumption and sedimentation levels of sulfuric acid during storage for different periods and at different temperatures were assessed. The characteristics of an asphalt binder

T. L. Denisova; A. F. Frolov; A. N. Aminov; S. P. Novosel'tsev

1987-01-01

263

[Modification of hyaluronic acid with aromatic amino acids].  

PubMed

Hyaluronic acid was modified with aromatic amino acids (5-aminosalicylic, 4-aminosalicylic, anthranilic, and p-aminobenzoic) in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The modified glycans contained 9-43% of arylamide groups and 10-33% of isoureidocarbonyl groups depending on the nature of the amino acid. Reduction with sodium borohydride allowed the conversion of isoureidocarbonyl groups into hydroxymethyl groups. PMID:15787219

Ponedel'kina, I Iu; Odinokov, V N; Vakhrusheva, E S; Golikova, M T; Khalilov, L M; Dzhemilov, U M

2005-01-01

264

Conversion of phenolics to lignans: Sinapic acid to thomasidioic acid  

Microsoft Academic Search

Changes in sinapic acid when exposed to aqueous alkaline conditions were elucidated. Sinapic acid was exposed to a volatile\\u000a buffer (pH 8.5) for 24 h, lyophilized, acidified, extracted, and characterized using nuclear magnetic resonance and mass spectroscopy.\\u000a The product obtained was identified as the lignan thomasidioic acid. This identification was confirmed by comparison with\\u000a a synthesized authentic sample of thomasidioic

M. I. Rubino; S. D. Arntfield; J. L. Charlton

1995-01-01

265

Molecular Structure of Butyric acid  

NSDL National Science Digital Library

n-Butyric acid is a substance that was isolated from butter in 1869. Butyric acid means, in Latin, the acid of butter as it was first discovered in rancid butter. It is found most commonly in butter, but can also be present in some fruits. Butyric acid is also produced synthetically, through fermentation of various carbohydrates, to be used as a flavoring agent in various food products. Applications of butyric acid are as an additive to food, flavorings, varnishes, perfumes, pharmaceuticals and disinfectants. It is also used for the production of plastics, plasticizers, surfactants and textile auxiliaries. Butyric acid and its derivatives are also being seriously considered around the world as potential anticancer agents.

2002-10-11

266

Shaping up nucleic acid computation  

PubMed Central

Summary of recent advances (abstract) Nucleic acid-based nanotechnology has always been perceived as novel, but has begun to move from theoretical demonstrations to practical applications. In particular, the large address spaces available to nucleic acids can be exploited to encode algorithms and/or act as circuits, and thereby process molecular information. In this review we revisit several milestones in the field of nucleic acid-based computation, but also highlight how the prospects for nucleic acid computation go beyond just a large address space. Functional nucleic acid elements (aptamers, ribozymes, and deoxyribozymes) can serve as inputs and outputs to the environment, and can act as logical elements. Into the future, the chemical dynamics of nucleic acids may prove as useful as hybridization for computation. PMID:20538451

Chen, Xi

2010-01-01

267

Molecular Structure of Salicylic acid  

NSDL National Science Digital Library

Salicylic acid is a colorless to white crystalline powder with a sweetish acrid taste that occurs naturally in many microorganisms and plants in very small amounts. It is also made synthetically and used as preservative of food products in some countries and as an antiseptic in mouthwashes and toothpastes. This chemical is also used in the manufacture of methyl salicylates, acetylasalicylic acid (aspirin) and other salicylates. Salicylic acid is a chemical intermediate in the synthesis of dyestuff, salicylate esters and salts. It is prepared commercially by heating sodium phenolate (the sodium salt of phenol) with carbon dioxide under pressure to form sodium salicylate, which is treated with sulfuric acid to liberate salicylic acid. Salicylic acid is quite irritating to skin and mucosa and it destroys epithelial cells. Absorption of large amounts can cause vomiting, abdominal pain, acidosis and mental disturbances.

2004-11-11

268

Clinical use of acid steatocrit.  

PubMed

Malabsorption of fat is an important gastrointestinal cause of malnutrition and growth retardation in childhood. The gold standard for the evaluation of fat malabsorption is the faecal fat balance method. The acid steatocrit method has recently been introduced as a simple method to evaluate faecal fat. The present study was aimed at evaluating the acid steatocrit in clinical practice. Faecal fat excretion and acid steatocrit results were determined in 42 children, half with and half without fat malabsorption. Acid steatocrit results correlated significantly with both faecal fat excretion (p < 0.01) and faecal fat concentration (p < 0.001). Sensitivity and specificity of the acid steatocrit for the diagnosis of malabsorption were 90% and 100%, respectively. We consider the acid steatocrit method useful for the screening and monitoring of patients with steatorrhoea. PMID:9183483

Van den Neucker, A; Pestel, N; Tran, T M; Forget, P P; Veeze, H J; Bouquet, J; Sinaasappel, M

1997-05-01

269

Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis.  

PubMed

Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end-product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA-producing Aureobasidium pullulans strain ZX-10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high-titer equivalent to 87.6?g/L of malic acid and high-productivity of 0.61?g/L?h in free-cell fermentation in a stirred-tank bioreactor. Fed-batch fermentations with cells immobilized in a fibrous-bed bioreactor (FBB) achieved the highest product titer of 144.2?g/L and productivity of 0.74?g/L?h. The fermentation produced PMA was purified by adsorption with IRA-900 anion-exchange resins, achieving a ?100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2?M sulfuric acid at 85°C, which followed the first-order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application. PMID:23436475

Zou, Xiang; Zhou, Yipin; Yang, Shang-Tian

2013-08-01

270

Racemization of Meteoritic Amino Acids  

Microsoft Academic Search

Meteorites may have contributed amino acids to the prebiotic Earth, affecting the global ratio of right-handed to left-handed (D\\/L) molecules. We calculate D\\/L ratios for seven biological, alpha-hydrogen, protein amino acids over a variety of plausible parent body thermal histories, based on meteorite evidence and asteroid modeling. We show that amino acids in meteorites do not necessarily undergo complete racemization

Barbara A. Cohen; Christopher F. Chyba

2000-01-01

271

Certain derivatives of aminomethylphosphonic acid  

Microsoft Academic Search

Summary 1.Experiments on the acylatlon of aminomethylphosphonic acid show that it proceeds with greater difficulty than the acylation of glycine. Acetamidomethyl-, (chloroacetamido)methyl-, and phthalimidamethyl-phosphonic acids have been prepared.2.The methylation of aminomethylphosphonic acid has been effected by means of methyl iodide in a methanol mediums, and it has been shown that a quaternary iodide derived from the phosphonobetaine is formed. It

Me Io Kabachnik; T. Ya. Medved

1953-01-01

272

Polyaminopolycarboxylic Acids derived from Polyethyleneamines  

Microsoft Academic Search

THE effects of increasing length of the alkylene bridge on acid dissociation constants and metal chelate stability constants of homologues of ethylene-diaminetetra-acetic acid derived from polymethylene-diamines have been reported within recent years1. The effects of an increase in the polydentate and polyelectrolyte nature of polyaminopolycarboxylic acids derived from polyethylene polyamines have not been investigated except for a brief report on

Albert E. Frost

1956-01-01

273

All-trans retinoic acid regulates hepatic bile acid homeostasis.  

PubMed

Retinoic acid (RA) and bile acids share common roles in regulating lipid homeostasis and insulin sensitivity. In addition, the receptor for RA (retinoid x receptor) is a permissive partner of the receptor for bile acids, farnesoid x receptor (FXR/NR1H4). Thus, RA can activate the FXR-mediated pathway as well. The current study was designed to understand the effect of all-trans RA on bile acid homeostasis. Mice were fed an all-trans RA-supplemented diet and the expression of 46 genes that participate in regulating bile acid homeostasis was studied. The data showed that all-trans RA has a profound effect in regulating genes involved in synthesis and transport of bile acids. All-trans RA treatment reduced the gene expression levels of Cyp7a1, Cyp8b1, and Akr1d1, which are involved in bile acid synthesis. All-trans RA also decreased the hepatic mRNA levels of Lrh-1 (Nr5a2) and Hnf4? (Nr2a1), which positively regulate the gene expression of Cyp7a1 and Cyp8b1. Moreover, all-trans RA induced the gene expression levels of negative regulators of bile acid synthesis including hepatic Fgfr4, Fxr, and Shp (Nr0b2) as well as ileal Fgf15. All-trans RA also decreased the expression of Abcb11 and Slc51b, which have a role in bile acid transport. Consistently, all-trans RA reduced hepatic bile acid levels and the ratio of CA/CDCA, as demonstrated by liquid chromatography-mass spectrometry. The data suggest that all-trans RA-induced SHP may contribute to the inhibition of CYP7A1 and CYP8B1, which in turn reduces bile acid synthesis and affects lipid absorption in the gastrointestinal tract. PMID:25175738

Yang, Fan; He, Yuqi; Liu, Hui-Xin; Tsuei, Jessica; Jiang, Xiaoyue; Yang, Li; Wang, Zheng-Tao; Wan, Yu-Jui Yvonne

2014-10-15

274

Organic Acid Production by Basidiomycetes  

PubMed Central

Sixty-seven strains belonging to 47 species of Basidiomycetes were examined for their acid-producing abilities in glucose media, in both the presence and absence of CaCO3, in stationary and shake cultures. Some strains were found to produce large quantities of oxalic acid. The oxalic acid-producing strains could be separated into two groups. Strains of one group (mostly brown-rot fungi) were able to produce oxalic acid, regardless of whether CaCO3 was present in the medium. Strains of the other group (mostly white-rot fungi) were characterized by their ability to produce oxalic acid only when CaCO3 was added to the medium. With the latter group, shake-culturing was generally more effective than stationary culturing in respect to acid production. In the CaCO3-containing media, Schizophyllum commune, Merulius tremellosus, and Porodisculus pendulus were found to produce substantial amounts of L-malic acid as a main metabolic product, along with small quantities of oxalic and other acids in shake cultures. Especially, S. commune and M. tremellosus may be employed as malic acid-producing species. PMID:5867653

Takao, Shoichi

1965-01-01

275

[Ulcer therapy without acid inhibition].  

PubMed

The mechanism of action of ulcer drugs without acid inhibition appears to involve improvement of defensive factors of the gastroduodenal mucosa. The concept of ulcer healing without acid inhibition is attractive for theoretical reasons, because doubts have arisen about the safety of elevation of intragastric pH, especially in long-term treatment of peptic ulcer disease. Ulcer drugs that do not affect gastric acidity may therefore be preferred, provided they compare favorably to the best acid inhibitors available in terms of efficacy, adverse effects and other requirements. Among these drugs, sucralfate fulfills these criteria to a large extent. PMID:6547542

Koelz, H R

1984-05-19

276

Molecular Structure of Lauric acid  

NSDL National Science Digital Library

Lauric acid was first discovered in lauraceae seeds by Marsson T in 1849. The highest content of lauric acid is found in a mother's breast milk and lauraceae seeds. It is used in foods such as vegetable shortenings as a defoaming agent and industrially as a booster for soaps and detergents. Also it is used in cosmetics, insecticides, and food additives. Additionally, Lauric acid is a medium chain fatty acid, which forms monolaurin in the human or animal body. This compound is an antiviral, antibacterial, and antiprotozoal monoglyceride that destroys lipid coated viruses such as HIV, herpes, cytomegalovirus, and influenza.

2002-10-11

277

Acidic gas capture by diamines  

DOEpatents

Compositions and methods related to the removal of acidic gas. In particular, the present disclosure relates to a composition and method for the removal of acidic gas from a gas mixture using a solvent comprising a diamine (e.g., piperazine) and carbon dioxide. One example of a method may involve a method for removing acidic gas comprising contacting a gas mixture having an acidic gas with a solvent, wherein the solvent comprises piperazine in an amount of from about 4 to about 20 moles/kg of water, and carbon dioxide in an amount of from about 0.3 to about 0.9 moles per mole of piperazine.

Rochelle, Gary (Austin, TX); Hilliard, Marcus (Missouri City, TX)

2011-05-10

278

The History of Acid Inhibition  

E-print Network

I review here the history of inhibition of gastric acid. References are limited to books and reviews in which detailed citations can be found. ANTACIDS In ancient times, acids were not understood in the modem chemical sense but merely as bitter sour liquids [1]. Some foods were thought acidic, and if the stomach had an ulcer, everything acrid was to be avoided and soothing remedies such as starch and milk used. Antacids neutralize, rather than inhibit, acid secretion but could not be rationally prescribed until acids were understood in the modern chemical sense. Hydrochloric acid has been known since the early fifteenth century, thought to be in the stomach by Paracelsus in the sixteenth and by Van Helmont in the seventeenth century, but it was not until 1823 that Prout definitively identified free hydrochloric acid in the gastric juice of man and animals and made quantitative measurements of its concentration. Antacids became widely used only this century, especially in association with Sippytype diets for ulcers [2]. As recently as the 1960s, orthodox gastroenterologists believed that gastric acidity was reduced by minimizing the amount of acid-stimulating foods such

J. H. Barona

1994-01-01

279

Acid rain on acid soil: a new perspective  

Microsoft Academic Search

Acid rain is widely believed to be responsible for acidifying soil and water in areas of North America and northern Europe. However, factors commonly considered to make landscapes susceptible to acidification by acid rain are the same factors long known to strongly acidify soils through the natural processes of soil formation. Recovery from extreme and widespread careless land use has

E. C. Krug; C. R. Frink

1983-01-01

280

Acid zeta function and ajoint acid zeta function  

E-print Network

In this paper we set up the theory of acid zeta function and ajoint acid zeta function, based on the theory, we point out a reason to doubt the truth of the Riemann hypothesis and also as a consequence, we give out some new RH equivalences.

Jining Gao

2010-03-16

281

Peptidases and amino acid catabolism in lactic acid bacteria  

Microsoft Academic Search

The conversion of peptides to free amino acids and their subsequent utilization is a central metabolic activity in prokaryotes. At least 16 peptidases from lactic acid bacteria (LAB) have been characterized biochemically and\\/or genetically. Among LAB, the peptidase systems of Lactobacillus helveticus and Lactococcus lactis have been examined in greatest detail. While there are homologous enzymes common to both systems,

Jeffrey E. Christensen; Edward G. Dudley; Jeffrey A. Pederson; James L. Steele

1999-01-01

282

Fast HPLC-ECD analysis of ascorbic acid, dehydroascorbic acid and uric acid.  

PubMed

A robust and rapid high-pressure liquid chromatography-electrochemical detection (HPLC-ECD) method was developed and validated for the accurate determination of ascorbic acid (AA) and uric acid (UA), in human plasma. Dehydroascorbic acid (DHAA) was indirectly measured by subtracting native ascorbic acid from total ascorbic acid concentrations; the latter was obtained after chemical reduction. A stable electrochemical active internal standard (homogentisic acid) was added for the accurate quantification of the analytes. The analyses were performed on a reverse-phase column with traditional HPLC and ultra-HPLC (UHPLC). The UHPLC method showed increased sensitivity with detection limit of 0.05ng for both AA and UA, 2 times lower compared to conventional HPLC. UHPLC also reduced run times fourfold with less waste generation. Both assays showed good accuracy and precision, the intra- and inter-day CVs of AA and UA analysis are less than 7%. PMID:19250886

Li, Xingnan; Franke, Adrian A

2009-04-01

283

40 CFR 141.601 - Standard monitoring.  

Code of Federal Regulations, 2010 CFR

...levels or the month of warmest water temperature. You must review available...TTHM or HAA5 levels or warmest water temperature. Source water type Population...or HAA5 levels or the warmest water temperature. (2) You must...

2010-07-01

284

40 CFR 141.601 - Standard monitoring.  

Code of Federal Regulations, 2011 CFR

...levels or the month of warmest water temperature. You must review available...TTHM or HAA5 levels or warmest water temperature. Source water type Population...or HAA5 levels or the warmest water temperature. (2) You must...

2011-07-01

285

Molecular Structure of Isophthalic acid  

NSDL National Science Digital Library

Isophthalic acid is one of the three simple aromatic dicarboxylic acids with the carboxyl groups in the meta postions. It is used to produce isophthalic polyester that together with other components is used in resin systems for flame retardants and in corrosion prevention.

2008-01-10

286

Acetic Acid Catalyzed Carbon Aerogels  

Microsoft Academic Search

We prepared carbon aerogels with a wide range of structural properties and densities using the weak acetic acid as a catalyst. Two series of acetic acid catalyzed carbon aerogels with different dilution of the catalyst and the monomers were investigated accurately. Structural investigation was performed via (U)SAXS, gas sorption and SEM. The pore and particle size can be tailored according

R. Brandt; R. Petricevic; H. Pröbstle; J. Fricke

2003-01-01

287

Acid rain & electric utilities II  

SciTech Connect

This document presents reports which were presented at the Acid Rain and Electric Utilities Conference. Topics include environmental issues and electric utilities; acid rain program overview; global climate change and carbon dioxide; emissions data management; compliance; emissions control; allowance and trading; nitrogen oxides; and assessment. Individual reports have been processed separately for the United States Department of Energy databases.

NONE

1997-12-31

288

Ricinoleic acid-based biopolymers.  

PubMed

Polyanhydrides synthesized from pure ricinoleic acid half-esters with maleic and succinic anhydrides possess desired physicochemical and mechanical properties for use as drug carriers. Ricinoleic acid maleate or succinate diacid half-esters were prepared from the reaction of crude ricinoleic acid (85% content) with succinic or maleic anhydride. The pure diacid monomers were obtained by chromatography purification through silica gel using petroleum ether/ethyl acetate/acetic acid (80/30/1 v/v/v) mixture as eluent. The pure diacid monomers (>99%) were polymerized by melt condensation to yield film-forming polymers with molecular weights exceeding 40,000 with a polydispersity of 2. Extensive biocompatibility study demonstrated their toxicological inertness and biodegradability. Their rate of elimination from rats in the course of about 4-6 weeks was faster than that found for similar fatty acid-based polyanhydrides previously tested. In vitro studies showed that these polymers underwent rapid hydrolytic degradation in 10 days. Methotrexate release from the polymers was not affected by the initial polymer molecular weight in the range of 10,000-35,000. The in vitro drug release correlated with the degradation of the polymers. The fatty acid ester monomers were further degraded to its counterparts, ricinoleic acid and succinic or maleic acid. PMID:10397984

Teomim, D; Nyska, A; Domb, A J

1999-06-01

289

Acid Precipitation: Causes and Consequences.  

ERIC Educational Resources Information Center

This article is the first of three articles in a series on the acid rain problem in recent years. Discussed are the causes of acid precipitation and its consequences for the abiotic and biotic components of the terrestrial and aquatic ecosystems, and for man-made materials. (Author/SA)

Babich, Harvey; And Others

1980-01-01

290

The Canadian acid rain strategy  

Microsoft Academic Search

In November 1994, Canadian Energy and Environment Ministers announced their intention to develop a long-term domestic acid rain strategy for post-2000. The strategy would address the need for further emission reductions within Canada as well as the need for further emission reductions in the United States for those sources and pollutants that result in continuing negative impacts from acid deposition

G Fenech

1998-01-01

291

The Acid Rain Differential Game  

Microsoft Academic Search

This paper considers an acid rain differential game. Countries emit sulphur which is partly transferred to other countries. Depositions above critical loads ultimately destroy the soil. Countries face a trade-off between the costs of emission reductions and the damage to the soil due to the depletion of the acid buffers. Because of the transboundary externalities the outcome will depend on

Karl-Göran Mäler; Aart De Zeeuw

1998-01-01

292

Acid-Base Titration Applet  

NSDL National Science Digital Library

Acid-Base titration applet that plots pH changes as student adds acid or base. Gives choice of indicators (only two right now). Compares plots for titration of traditional solution and a buffered solution (several choices for comparison). Can alter starting concentrations.

Usc

293

Acid rain: facts and fallacies  

Microsoft Academic Search

Acid rain is a complex environmental problem that is hard to define in terms of sources and effects. Major sources are thought to be atmospheric emissions, mostly from urban sources, although exact locations and the means by which emissions are transformed to acid rain are not entirely clear. Lack of long-term records has made it difficult to determine how fast

1981-01-01

294

Acid Resistance in Mycobacterium tuberculosis  

Microsoft Academic Search

Responses to acid have been studied extensively in enteric pathogens, such as Escherichia coli, Vibrio cholerae, and Heli- cobacter pylori that encounter the extremely low pH (pH 2 to 3) of the stomach during ingestion. In contrast, much less is known about how obligate or facultative intracellular bacterial pathogens like Mycobacterium tuberculosis respond, resist, and persist in the moderately acid

Omar H. Vandal; Carl F. Nathan; Sabine Ehrt

2009-01-01

295

Acid Rain: A Background Report.  

National Technical Information Service (NTIS)

This Staff Brief was prepared for the Wisconsin Legislative Council's Special Committee on Acid Rain to provide an introduction to the issue of acid rain. It is divided into four parts. Part I provides an overview on the controversies surrounding the meas...

L. Glustrom, J. Stolzenberg

1982-01-01

296

Advanced Lead Acid Battery Development.  

National Technical Information Service (NTIS)

Researchers at the University of Idaho have been investigating the possibility of using lead acid batteries in electric and hybrid vehicles for more than ten years, and the funding from UTC Program helped support this continuing effort. The lead acid batt...

D. Edwards, C. Kinney

2001-01-01

297

SOIL REACTION AND ACIDIC DEPOSITION  

EPA Science Inventory

This chapter discusses the major chemical processes by which acidic deposition interacts with soils. he focus is on forest soils, as the effects of acidic deposition on soils used for production of food and fiber are generally small compared to effects of agricultural practices s...

298

SIMULATED ACID RAIN ON CROPS  

EPA Science Inventory

In 1981, simulated H2SO4 acid rain was applied to alfalfa and tall fescue and a 2:1 ratio of H2SO4:HNO3 acid rain was applied to alfalfa, tall fescue, barley, wheat, potato, tomato, radish, and corn crops growing in the open field at Corvallis, Oregon. Careful attention was given...

299

Bioelectric neutralization of acid waters  

Microsoft Academic Search

An apparatus is to be used in a process for bioelectric neutralization of a body of water having a bottom of anaerobic mud and an acid supernatant liquid. The apparatus comprises a buoy riding on the surface of the water, and upper electrode preferably of carbon suspended from the buoy in the acid supernatant liquid, a lower electrode preferably of

F. D. Sisler; F. E. Senftle

1978-01-01

300

Acetic acid bacteria in oenology  

Microsoft Academic Search

Acetic acid bacteria have always been considered the bad mi- croorganisms of oenology; responsible for wine spoiling (vine- gary taint). The taxonomy and our knowledge of the metabo- lism of acetic acid bacteria are rapidly evolving, especially as new molecular biology techniques are applied to this fastidious group of microorganisms, which are still rather difficult to work with. The dramatic

A. Mas; M. J. Torija; A. González; M. Poblet; J. M. Guillamón

301

Acid Tests and Basic Fun.  

ERIC Educational Resources Information Center

Explores acids and bases using different indicators, such as turmeric, purple grape juice, and lichens. Because some of these indicators are not as sensitive as cabbage juice or litmus paper, determining to which acids and bases each indicator is sensitive presents an enjoyable, problem-solving challenge for students. Presents directions for…

McBride, John W.

1995-01-01

302

Molecular Structure of Formic acid  

NSDL National Science Digital Library

Formic Acid, also known as methanoic acid and hydrogencarboxylic acid, is the simplest organic acid. It is a colorless, toxic, corrosive liquid with a pungent, penetrating odor. In nature, it is found in the stings and bites of many insects of the order hymenoptera, including bees and ants. The principal use of formic acid is as a preservative and antibacterial agent in livestock feed. The largest single use of formic acid is as a silage additive in Europe, but this market hardly exists in the United States. When sprayed on fresh hay or other silage, it arrests certain decay processes and causes the feed to retain its nutritive value longer. In the poultry industry, it is sometimes added to silage to kill salmonella bacteria. It is also used in textile dyeing, leather tanning, as a solvent, in electroplating processes, in the manufacturing of lacquers, glass, vinyl resin plasticizers, and formate esters (for flavor and fragrance) and in the manufacture of fumigants. Formic acid is a strong reducing agent, and may act both as an acid and as an aldehyde because the carboxyl is bound to a hydrogen rather than an alkyl group.

2003-05-08

303

Acid precipitation in historical perspective  

Microsoft Academic Search

The history of acid precipitation is traced from the first awareness of the problem in the mid-17th century to the present. An outline of the National Acid Precipitation Assessment program is also given, and the author makes recommendations for future research. (JMT)

Ellis B. Cowling

1982-01-01

304

BOTANICAL ASPECTS OF ACIDIC PRECIPITATION  

EPA Science Inventory

Acidic precipitation can be characterized as wet or frozen atmospheric deposition with a hydrogen ion concentration greater than 2.5 microequivalents liter-1. Acidic precipitation is perceived as a significant air pollution problem derived chiefly from combustion of fossil fuels,...

305

Distillation Separation of Hydrofluoric Acid and Nitric Acid from Acid Waste Using the Salt Effect on Vapor-Liquid Equilibrium  

NASA Astrophysics Data System (ADS)

This study presents the distillation separation of hydrofluoric acid with use of the salt effect on the vapor-liquid equilibrium for acid aqueous solutions and acid mixtures. The vapor-liquid equilibrium of hydrofluoric acid + salt systems (fluorite, potassium nitrate, cesium nitrate) was measured using an apparatus made of perfluoro alkylvinylether. Cesium nitrate showed a salting-out effect on the vapor-liquid equilibrium of the hydrofluoric acid-water system. Fluorite and potassium nitrate showed a salting-in effect on the hydrofluoric acid-water system. Separation of hydrofluoric acid from an acid mixture containing nitric acid and hydrofluoric acid was tested by the simple distillation treatment using the salt effect of cesium nitrate (45 mass%). An acid mixture of nitric acid (5.0 mol · dm-3) and hydrofluoric acid (5.0 mol · dm-3) was prepared as a sample solution for distillation tests. The concentration of nitric acid in the first distillate decreased from 5.0 mol · dm-3 to 1.13 mol · dm-3, and the concentration of hydrofluoric acid increased to 5.41 mol · dm-3. This first distillate was further distilled without the addition of salt. The concentrations of hydrofluoric acid and nitric acid in the second distillate were 7.21 mol · dm-3 and 0.46 mol · dm-3, respectively. It was thus found that the salt effect on vapor-liquid equilibrium of acid mixtures was effective for the recycling of acids from acid mixture wastes.

Yamamoto, Hideki; Sumoge, Iwao

2011-03-01

306

Atmospheric dust and acid rain  

SciTech Connect

Why is acid rain still an environmental problem in Europe and North America despite antipollution reforms? The answer really is blowing in the wind: atmospheric dust. These airborne particles can help neutralize the acids falling on forests, but dust levels are unusually low these days. In the air dust particles can neutralize acid rain. What can we do about acid rain and atmospheric dust? Suggestions range from the improbable to the feasible. One reasonable suggestion is to reduce emissions of acidic pollutants to levels that can be buffered by natural quantities of basic compounds in the atmosphere; such a goal would mean continued reductions in sulfur dioxide and nitrogen oxides, perhaps even greater than those prescribed in the 1990 Amendments to the Clean Air Act in the U.S. 5 figs.

Hedin, L.O.; Likens, G.E.

1996-12-01

307

Direct formic acid fuel cells  

NASA Astrophysics Data System (ADS)

The performance of formic acid fuel oxidation on a solid PEM fuel cell at 60 °C is reported. We find that formic acid is an excellent fuel for a fuel cell. A model cell, using a proprietary anode catalyst produced currents up to 134 mA/cm 2 and power outputs up to 48.8 mW/cm 2. Open circuit potentials (OCPs) are about 0.72 V. The fuel cell runs successfully over formic acid concentrations between 5 and 20 M with little crossover or degradation in performance. The anodic polarization potential of formic acid is approximately 0.1 V lower than that for methanol on a standard Pt/Ru catalyst. These results show that formic acid fuel cells are attractive alternatives for small portable fuel cell applications.

Rice, C.; Ha, S.; Masel, R. I.; Waszczuk, P.; Wieckowski, A.; Barnard, Tom

308

Fumaric acid production by fermentation.  

PubMed

The potential of fumaric acid as a raw material in the polymer industry and the increment of cost of petroleum-based fumaric acid raises interest in fermentation processes for production of this compound from renewable resources. Although the chemical process yields 112% w/w fumaric acid from maleic anhydride and the fermentation process yields only 85% w/w from glucose, the latter raw material is three times cheaper. Besides, the fermentation fixes CO2. Production of fumaric acid by Rhizopus species and the involved metabolic pathways are reviewed. Submerged fermentation systems coupled with product recovery techniques seem to have achieved economically attractive yields and productivities. Future prospects for improvement of fumaric acid production include metabolic engineering approaches to achieve low pH fermentations. PMID:18214471

Roa Engel, Carol A; Straathof, Adrie J J; Zijlmans, Tiemen W; van Gulik, Walter M; van der Wielen, Luuk A M

2008-03-01

309

Fumaric acid production by fermentation  

PubMed Central

The potential of fumaric acid as a raw material in the polymer industry and the increment of cost of petroleum-based fumaric acid raises interest in fermentation processes for production of this compound from renewable resources. Although the chemical process yields 112% w/w fumaric acid from maleic anhydride and the fermentation process yields only 85% w/w from glucose, the latter raw material is three times cheaper. Besides, the fermentation fixes CO2. Production of fumaric acid by Rhizopus species and the involved metabolic pathways are reviewed. Submerged fermentation systems coupled with product recovery techniques seem to have achieved economically attractive yields and productivities. Future prospects for improvement of fumaric acid production include metabolic engineering approaches to achieve low pH fermentations. PMID:18214471

Roa Engel, Carol A.; Zijlmans, Tiemen W.; van Gulik, Walter M.; van der Wielen, Luuk A. M.

2008-01-01

310

Molecular Structure of Stearic acid  

NSDL National Science Digital Library

Stearic acid is white leaflets, slightly yellow crystal masses or a white to slightly yellow powder. Stearic acid is a saturated fatty acid found in low percentages in cotton, coconut, palm kernel, corn, palm, castor, rapeseed, soybean, sunflower, herring, and tallow oils. It is also one of the fat components found in the cocoa butter of chocolate. It is prepared synthetically by hydrogenation of cottonseed and other vegetable oils or by treating animal fat with water at a high pressure and temperature. Stearic acid is useful as an ingredient in making candles, soaps, and for softening synthetic rubber. It is also a component of cosmetic formulations, pharmaceuticals creams and vanishing lotion. Stearic acid is practically nontoxic but the dust is irritating to eyes, nose, and throat and the solid is irritating to skin and eyes.

2004-11-11

311

Molecular Structure of Galacturonic acid  

NSDL National Science Digital Library

Galacturonic acid is the monobasic acid resulting from oxidation of the primary alcohol group of D-galactose to carboxyl. It is widely distributed as a constituent of pectins (compounds with heterogeneous grouping of acidic structural polysaccharides, found in fruit and vegetables), many plant gums, and mucilages (gummy substances obtained from certain plants, which are used as food stabilizers). Gums tend to be used as thickening and bulking agents in pharmaceutics, and they play a less obvious part in most plants. Once swallowed, their actions are no different from those of the mucilages. D-Galacturonic acid prepared from pectin can be used to synthesize vitamin C. Native pectin is a mixture of polysaccharides, with the major component a polymer of -D-galacturonic acid. Pectin has numerous other medical and pharmaceutical uses, for example in combination with plant hemicelluloses and lignin, may be useful dietary constituents in preventing coronary heart disease, diverticular disease, ulcerative colitis, and a variety of other Western diseases.

2003-05-08

312

Molecular Structure of Linoleic acid  

NSDL National Science Digital Library

Linoleic acid is a polyunsaturated fatty acid occurring widely in plant glycerides or fats. Common sources include many vegetable oils such as flax seed, safflower, soybean, peanut, and corn; some margarines; and dairy fats. It is a colorless to straw-colored liquid, insoluble in water, but soluble in alcohol and ether. Linoleic acid is easily oxidized by air and is combustible. It also appears as an aluminum salt, in the form of yellow lumps or powder, that is practically insoluble in water but soluble in oils and fixed alkalai hydroxides. Linoleic acid is essential in human nutrition and is used also for soaps, animal feeds, paints, drying protective coatings, emulsifying or smoothing and wetting agents, and in biochemical research. The conjugated form of linoleic acid or CLA has been associated with health benefits such as lowered risk of cancer and atherosclerosis. Prepared CLA is available as a supplement. However, foods high in CLA content could be used.

2003-05-08

313

Synthesis of l-(+)-Tartaric Acid from l-Ascorbic Acid via 5-Keto-d-Gluconic Acid in Grapes  

PubMed Central

5-Keto-l-idionic acid (?5-keto-d-gluconic acid, d-xylo-5-hexulosonic acid) was found as a metabolic product of l-ascorbic acid in slices of immature grapes, Vitis labrusca L. cv `Delaware'. Specifically labeled compounds, recognized as metabolic products of l-ascorbic acid in grapes, were fed to young grape tissues to investigate the metabolic pathway from l-ascorbic acid to l-(+)-tartaric acid. Label from dehydro-l-[1-14C]ascorbic acid, 2-keto-l-[1-14C]idonic acid (l-xylo-2-hexulosonic acid), l-[1-14C]idonic acid, or 5-keto-l-[1-14C] idonic acid was incorporated into l-(+)-tartaric acid in high yields as it was in the l-[1-14C]ascorbic acid experiment. In a double label experiment involving a mixture of l-[1-14C]idonic acid and l-[2-3H]idonic acid, the 3H/14C ratios of 5-keto-l-idonic acid and l-(+)-tartaric acid synthesized in young grape leaves were almost the same as the value of the l-idonic acid fed. Label from 5-keto-l-[6-14C]idonic acid was incorporated into sugars and insoluble residue in the same way as l-[6-14C]ascorbic acid was metabolized in grapes. These results provide strong evidence that in grapes l-(+)-tartaric acid is synthesized from the C4 fragment that corresponds to the C1 to C4 group of the 5-keto-l-idonic acid derived from l-ascorbic acid via 2-keto-l-idonic acid and l-idonic acid. PMID:16663792

Saito, Kazumi; Kasai, Zenzaburo

1984-01-01

314

The ascorbic acid paradox.  

PubMed

Ascorbic acid (AA) is a common culture medium and dietary supplement. While AA is most commonly known for its antioxidant properties, it is also known to function as a pro-oxidant under select conditions. However, the complexity and often unknown composition of biological culture systems makes prediction of AA behaviour in supplemented cultures challenging. The frequent observation of outcomes inconsistent with antioxidant behaviour suggests that AA may be playing a pro-oxidant role more often than appreciated. In this work we explored the intracellular and extracellular impact of AA supplementation on KG1a myeloid leukaemia cells over a 24-h culture period following the addition of the AA supplement. At 24h we found that supplementation of AA up to 250?M resulted in intracellular antioxidant behaviour. However, when these same cultures were evaluated at 2 or 4h we observed pro-oxidant activity at the higher AA concentrations indicating that the outcome was very much time and dose dependent. In contrast, pro-oxidant activity was never observed in the extracellular medium. Paradoxically, and to our knowledge not previously reported, we observed that intracellular pro-oxidant activity and extracellular antioxidant activity could occur simultaneously. These results indicate that the precise activity of AA supplementation varies as a function of dose, time and cellular location. Further, these results demonstrate how in the absence of careful culture characterization the true impact of AA on cultures could be underappreciated. PMID:20732307

Osiecki, Michael; Ghanavi, Parisa; Atkinson, Kerry; Nielsen, Lars K; Doran, Michael R

2010-10-01

315

Lead-acid battery  

NASA Technical Reports Server (NTRS)

A light weight lead-acid battery (30) having a positive terminal (36) and a negative terminal (34) and including one or more cells or grid stacks having a plurality of vertically stacked conductive monoplates (10, 20) with positive active material and negative active material deposited on alternating plates in the cell or grid stack. Electrolyte layers (26, 28) positioned between each monoplate are included to provide a battery cell having four sides which is capable of being electrically charged and discharged. Two vertical positive bus bars (42, 43) are provided on opposite sides of the battery cell for connecting the monoplates (10) with positive active material together in parallel current conducting relation. In addition, two negative bus bars (38, 39) on opposite sides of the battery cell each being adjacent the positive bus bars are provided for connecting the monoplates (20) with negative active material together in parallel current conducting relation. The positive (42, 43) and negative (38, 39) bus bars not only provide a low resistance method for connecting the plurality of conductive monoplates of their respective battery terminals (36, 34) but also provides support and structural strength to the battery cell structure. In addition, horizontal orientation of monoplates (10, 20) is provided in a vertical stacking arrangement to reduce electrolyte stratification and short circuiting due to flaking of positive and negative active materials from the monoplates.

Rowlette, John J. (Inventor)

1983-01-01

316

Acid hydrolysis of sugarcane bagasse for lactic acid production.  

PubMed

In order to use sugarcane bagasse as a substrate for lactic acid production, optimum conditions for acid hydrolysis of the bagasse were investigated. After lignin extraction, the conditions were varied in terms of hydrochloric (HCl) or sulfuric (H(2)SO(4)) concentration (0.5-5%, v/v), reaction time (1-5h) and incubation temperature (90-120 degrees C). The maximum catalytic efficiency (E) was 10.85 under the conditions of 0.5% of HCl at 100 degrees C for 5h, which the main components (in gl(-1)) in the hydrolysate were glucose, 1.50; xylose, 22.59; arabinose, 1.29; acetic acid, 0.15 and furfural, 1.19. To increase yield of lactic acid production from the hydrolysate by Lactococcus lactis IO-1, the hydrolysate was detoxified through amberlite and supplemented with 7 g l(-1) of xylose and 7 g l(-1) of yeast extract. The main products (in gl(-1)) of the fermentation were lactic acid, 10.85; acetic acid, 7.87; formic acid, 6.04 and ethanol, 5.24. PMID:19766480

Laopaiboon, Pattana; Thani, Arthit; Leelavatcharamas, Vichean; Laopaiboon, Lakkana

2010-02-01

317

Formation of acrylic acid from lactic acid in supercritical water  

SciTech Connect

Supercritical (SC) water is an unusual medium in which fast and specific heterolytic reactions can be conducted at temperatures as high as 400{degree}C. In supercritical water, lactic acid decomposes into gaseous and liquid products via three primary reaction pathways. Products of the acid-catalyzed heterolytic decarbonylation pathway are carbon monoxide, water, and acetaldehyde. Products of the homolytic, decarboxylation pathway are carbon dioxide, hydrogen, and acetaldehyde. Products of the heterolytic, dehydration pathway are acrylic acid and water. The intramolecular nucleophilic displacement of the {alpha}-hydroxyl by the carbonyl group of lactic acid, producing {alpha}-propiolactone as an unstable intermediate which subsequently rearranges to become the unsaturated acid, is a likely mechanism for acrylic acid formation, although an intramolecular E2 elimination initiated by attack of the carbonyl oxygen on a methyl hydrogen cannot be ruled out. Support for the former mechanism comes in part from the observed 100% relative yield of acrylic acid from {beta}-propiolactone in SC water.

Mok, W.S.L.; Antal, M.J. Jr. (Univ. of Hawaii, Honolulu (USA)); Jones, M. Jr. (Princeton Univ., NJ (USA))

1989-09-15

318

Reduction of hypervalent chromium in acidic media by alginic acid.  

PubMed

Selective oxidation of carboxylate groups present in alginic acid by Cr(VI) affords CO2, oxidized alginic acid, and Cr(III) as final products. The redox reaction afforded first-order kinetics in [alginic acid], [Cr(VI)], and [H(+)], at fixed ionic strength and temperature. Kinetic studies showed that the redox reaction proceeds through a mechanism which combines Cr(VI)?Cr(IV)?Cr(II) and Cr(VI)?Cr(IV)?Cr(III) pathways. The mechanism was supported by the observation of free radicals, CrO2(2+) and Cr(V) as reaction intermediates. The reduction of Cr(IV) and Cr(V) by alginic acid was independently studied and it was found to occur more than 10(3) times faster than alginic acid/Cr(VI) reaction, in acid media. At pH 1-3, oxo-chromate(V)-alginic acid species remain in solution during several hours at 15°C. The results showed that this abundant structural polysaccharide present on brown seaweeds is able to reduce Cr(VI/V/IV) or stabilize high-valent chromium depending on pH value. PMID:25263857

Bertoni, Fernando A; Bellú, Sebastian E; González, Juan C; Sala, Luis F

2014-12-19

319

Kinetics of aluminum-fulvic acid complexation in acidic waters  

SciTech Connect

A fluorescence technique has been used to study the complex formation kinetics of aluminum with a single metal-free fulvic acid isolated from an Adirondack Mountain forest soil. In the pH range of 3.0-4.5, two kinetically distinguishable components of the fulvic acid mixture have been identified, which define two types of average aluminum binding sites. Both fulvic acid average sites conform to a bidentate chelating binding site kinetic analysis, from which rate and equilibrium parameters have been obtained. From comparison of rate and equilibrium constants of aluminum-salicyclic acid complexation, the authors conclude that the faster reacting component of fulvic acid probably contains salicyclic acid type aluminum binding sites. Results are also compared with those of an aluminum-fluoride kinetic study. Fulvic acid and fluoride react with aluminum by the same mechanism and therefore have the same pH dependence. The dependence of the rate on temperature is, however, quite different for the two reactions. The environmental implications of these findings are discussed. 45 references, 5 figures, 6 tables.

Plankey, B.J.; Patterson, H.H.

1987-06-01

320

?-Oxidation of ?-Chlorinated Fatty Acids  

PubMed Central

Myeloperoxidase-derived HOCl targets tissue- and lipoprotein-associated plasmalogens to generate ?-chlorinated fatty aldehydes, including 2-chlorohexadecanal. Under physiological conditions, 2-chlorohexadecanal is oxidized to 2-chlorohexadecanoic acid (2-ClHA). This study demonstrates the catabolism of 2-ClHA by ?-oxidation and subsequent ?-oxidation from the ?-end. Mass spectrometric analyses revealed that 2-ClHA is ?-oxidized in the presence of liver microsomes with initial ?-hydroxylation of 2-ClHA. Subsequent oxidation steps were examined in a human hepatocellular cell line (HepG2). Three different ?-chlorinated dicarboxylic acids, 2-chlorohexadecane-(1,16)-dioic acid, 2-chlorotetradecane-(1,14)-dioic acid, and 2-chloroadipic acid (2-ClAdA), were identified. Levels of 2-chlorohexadecane-(1,16)-dioic acid, 2-chlorotetradecane-(1,14)-dioic acid, and 2-ClAdA produced by HepG2 cells were dependent on the concentration of 2-ClHA and the incubation time. Synthetic stable isotope-labeled 2-ClHA was used to demonstrate a precursor-product relationship between 2-ClHA and the ?-chlorinated dicarboxylic acids. We also report the identification of endogenous 2-ClAdA in human and rat urine and elevations in stable isotope-labeled urinary 2-ClAdA in rats subjected to intraperitoneal administration of stable isotope-labeled 2-ClHA. Furthermore, urinary 2-ClAdA and plasma 2-ClHA levels are increased in LPS-treated rats. Taken together, these data show that 2-ClHA is ?-oxidized to generate ?-chlorinated dicarboxylic acids, which include ?-chloroadipic acid that is excreted in the urine. PMID:20956542

Brahmbhatt, Viral V.; Albert, Carolyn J.; Anbukumar, Dhanalakshmi S.; Cunningham, Bryce A.; Neumann, William L.; Ford, David A.

2010-01-01

321

Analysis of Acidic Drugs in Swiss Wastewaters  

Microsoft Academic Search

Five acidic drugs (clofibric acid, ibuprofen, ketoprofen, mefenamic acid and diclofenac) were chosen in order to determine their behavior in a sewage treatment plant (STP). An analytical method using solid phase extraction (SPE) and a gas chromatograph coupled with a mass spectrometer (GC-MS) was used. The results show that four pharmaceuticals (clofibric acid, ketoprofen, mefenamic acid and diclofenac) are not

Benedicte Soulet; Annick Tauxe; Joseph Tarradellas

2002-01-01

322

Combined Acid Catalysis for Asymmetric Synthesis  

E-print Network

Combined Acid Catalysis for Asymmetric Synthesis Michael T. Corbett University of North Carolina, 44, 1924­1942. Limitations of classical Brønsted/Lewis Acid catalysis: · Poor reactivity (low acidity) · Low selectivity · High catalyst loading R X R X HMLn X Lewis Acid Catalysis Brønsted Acid Catalysis X

Johnson, Jeff S.

323

ACID RAIN DEGRADATION OF NYLON (POLYAMIDE, PHOTODEGRADATION)  

Microsoft Academic Search

Acid rain, precipitation with a ph less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid

KAREN E KYLLO

1984-01-01

324

Terahertz spectrum of gallic acid  

NASA Astrophysics Data System (ADS)

Gallic acid is natural polyphenol compound found in many green plants. More and more experiments have demonstrated that the gallic acid has comprehensive applications. In the field of medicine, the gallic acid plays an important role in antianaphylaxis, antineoplastic, antimycotic, anti-inflammatory, antivirotic, antiasthmatic and inhibiting the degradation of insulin. It also has a lot of applications in chemical industry, food industry and light industry. So it is important to study the terahertz time-domain spectroscopy of gallic acid. Terahertz time-domain spectroscopy (THz-TDS) is a new coherent spectral technology based on the femtosecond laser. In this work, the spectral characteristics of gallic acid in the range of 0.4 THz to 2.6 THz have been measured by THz-TDS. We obtained its absorption and refraction spectra at room temperature. The vibration absorption spectrum of the single molecule between 0.4 THz and 2.6 THz is simulated based on the Density Functional Theory (DFT). It is found that the gallic acid has the spectral response to THz wave in this frequency range. The results show the abnormal dispersion at 1.51 THz and 2.05 THz. These results can be used in the qualitative analysis of gallic acid and the medicine and food inspection.

Wu, Meng; Zhao, Guozhong; Wang, Haiyan; Liang, Chengshen

2009-11-01

325

Diabetes and Alpha Lipoic Acid  

PubMed Central

Diabetes mellitus is a multi-faceted metabolic disorder where there is increased oxidative stress that contributes to the pathogenesis of this debilitating disease. This has prompted several investigations into the use of antioxidants as a complementary therapeutic approach. Alpha lipoic acid, a naturally occurring dithiol compound which plays an essential role in mitochondrial bioenergetic reactions, has gained considerable attention as an antioxidant for use in managing diabetic complications. Lipoic acid quenches reactive oxygen species, chelates metal ions, and reduces the oxidized forms of other antioxidants such as vitamin C, vitamin E, and glutathione. It also boosts antioxidant defense system through Nrf-2-mediated antioxidant gene expression and by modulation of peroxisome proliferator activated receptors-regulated genes. ALA inhibits nuclear factor kappa B and activates AMPK in skeletal muscles, which in turn have a plethora of metabolic consequences. These diverse actions suggest that lipoic acid acts by multiple mechanisms, many of which have only been uncovered recently. In this review we briefly summarize the known biochemical properties of lipoic acid and then discussed the oxidative mechanisms implicated in diabetic complications and the mechanisms by which lipoic acid may ameliorate these reactions. The findings of some of the clinical trials in which lipoic acid administration has been tested in diabetic patients during the last 10?years are summarized. It appears that the clearest benefit of lipoic acid supplementation is in patients with diabetic neuropathy. PMID:22125537

Golbidi, Saeid; Badran, Mohammad; Laher, Ismail

2011-01-01

326

Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.  

PubMed

A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ? Erie > Huron > Superior ? Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid. PMID:22722738

Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

2012-11-01

327

Acidity dependence of the trifluoromethanesulfonic acid catalyzed isobutane-isobutylene alkylation modified with trifluoroacetic acid or water  

Microsoft Academic Search

Trifluoromethanesulfonic acid (TFSA) catalyzed isobutane-isobutylene alkylation modified with trifluoroacetic acid (TFA) or water, was studied over a wide range of acidity (Ho: ?10.1 to ?14.1). The effect of the acidity of these nonoxidizing strong mixed acid systems on the alkylation, is reported. For both systems, the best alkylation conditions were those at an acid strength of about Ho= ?10.7, giving

George A. Olah; Patrice Batamack; Denis Deffieux; Béla Török; Qi Wang; Árpád Molnár; G. K. Surya Prakash

1996-01-01

328

40 CFR 141.64 - Maximum contaminant levels for disinfection byproducts.  

Code of Federal Regulations, 2010 CFR

...with the maximum contaminant levels for TTHM and HAA5 identified...with the maximum contaminant levels for TTHM and HAA5 identified...with the maximum contaminant levels for TTHM and HAA5 identified...distribution system and storage tank management to reduce residence...

2010-07-01

329

40 CFR 721.2086 - Coco acid triamine condensate, polycarboxylic acid salts.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Coco acid triamine condensate, polycarboxylic acid salts. 721.2086 Section 721.2086 Protection...Specific Chemical Substances § 721.2086 Coco acid triamine condensate, polycarboxylic acid...

2013-07-01

330

Solid acids for green chemistry.  

PubMed

Solid acids and especially those based on micelle-templated silicas and other mesoporous high surface area support materials are beginning to play a significant role in the greening of fine and specialty chemicals manufacturing processes. A wide range of important organic reactions can be efficiently catalyzed by these materials, which can be designed to provide different types of acidity as well as high degrees of reaction selectivity. The solid acids generally have high turnover numbers and can be easily separated from the organic components. The combination of this chemistry with innovative reaction engineering offers exciting opportunities for innovative green chemical manufacturing in the future. PMID:12234209

Clark, James H

2002-09-01

331

Treatment of acid mine wastewaters  

SciTech Connect

Acid mine drainage often results from the oxidation sulfide minerals to form sulfuric acid. As a consequence, high concentrations of metals in the both the suspended and dissolved state result from the low pH water. This paper discusses several of the more common treatment methods for acid mine drainage including the use of chemical precipitation agents, pH correction agents, filtration methods, and biodegradation methods. Advanced treatment technologies are also briefly described and include microfiltration, reverse osmosis, ion exchange, and electrodialysis.

Hayward, D.; Barnard, R.

1993-06-01

332

Can crops tolerate acid rain  

SciTech Connect

This brief article describes work by scientists at the ARS Air Quality-Plant Growth and Development Laboratory in Raleigh, North Carolina, that indicates little damage to crops as a result of acid rain. In studies with simulated acid rain and 216 exposed varieties of 18 crops, there were no significant injuries nor was there reduced growth in most species. Results of chronic and acute exposures were correlated in sensitive tomato and soybean plants and in tolerant winter wheat and lettuce plants. These results suggest that 1-hour exposures could be used in the future to screen varieties for sensitivity to acid rain.

Kaplan, J.K.

1989-11-01

333

Chemiluminescent measurement of atmospheric acid  

NASA Technical Reports Server (NTRS)

The design and construction of a gas phase acid sensitive analyzer are reported. These studies showed that the chemical system was a practical analytical method. A complete instrument was developed and prepared for field testing. A Titan 3-C rocket was scheduled for launching on February 11, 1974. Through preparations made by NASA Langley the instrument was set up to monitor the acid concentration in the rocket exhaust. Due to adverse wind conditions no acid was detected. This entire trip is described in detail.

Stedman, D. H.; Kok, G. L.

1974-01-01

334

Be an acid rain detective  

SciTech Connect

Acid rain is discussed in a question and answer format. The article is aimed at educating sport fishermen on the subject, and also to encourage them to write their congressmen, senators, and the President about the acid rain problem. The article also announces the availability of an acid rain test kit available through the magazine, ''Sports Afield.'' The kit consists of pH-test paper that turns different shades of pink and blue according to the pH of the water tested. The color of the test paper is then compared to a color chart furnished in the kit and an approximate pH can be determined.

Atwill, L.

1982-07-01

335

Organic acids enhance halogen activation on mildly acidic water surfaces  

NASA Astrophysics Data System (ADS)

Iodine species of marine origin are ubiquitous in the marine boundary layer (MBL). They are found over the open ocean (even in the absence of biogenic sources), the Antarctic coast, in rain, aerosols, ice, and snow, and participate in HOx/NOx cycles in the MBL. Surface-active organic acids coating the surface marine microlayer (SML) and marine aerosols could affect their chemical/physical properties. Recent field measurements show that organic acids represent ˜50% of the mass of fog waters collected in the US Gulf Coast. Here we report that I2(g) emissions from the heterogeneous reactions of O3(g) with I- (aq) are dramatically enhanced in the presence of surface-active organic acids under mildly acidic condition that are typical of fine marine aerosols. The amphiphilic weak carboxylic acids appear to promote I2(g) emissions by donating the interfacial protons more efficiently than water itself. We infer that the organic acids coating aerosol particles ejected from ocean's surface films could enhance I2(g) production in the MBL.

Hayase, S.; Enami, S.; Yabushita, A.; Kawasaki, M.; Hoffmann, M. R.; Colussi, A. J.

2011-12-01

336

Genetics Home Reference: Sialic acid storage disease  

MedlinePLUS

... testing OMIM Genetic disorder catalog Conditions > Sialic acid storage disease On this page: Description Genetic changes Inheritance ... definitions Reviewed February 2008 What is sialic acid storage disease? Sialic acid storage disease is an inherited ...

337

Background on Net Acid or ARD Potential  

E-print Network

balance that favours net acidity or net alkalinity #12;01-3 ABA Method · For example, we want to calculate acid generating and the amount of acid is determined by titration and expressed in the same units

Boisvert, Jeff

338

Separation of saturated\\/unsaturated fatty acids  

Microsoft Academic Search

Fatty acid mixtures can be separated into one fraction rich in saturated fatty acids and the other rich in unsaturated acids.\\u000a Since saturated fatty acids have a higher melting point than unsaturated, liquid mixture to be fractionated is cooled to a\\u000a temperature at which the larger part of the saturated acids crystallize, while the greater part of unsaturated acids remain

G. Haraldsson

1984-01-01

339

Quantitative Paper Partition Chromatography of Sialic Acids  

Microsoft Academic Search

RECENTLY, it has been obvious that in most biological materials N-acetylsialic acid (N-acetyl-neuraminic acid) and N-glycolloylsialic acid occur together. By the introduction of a micromethod for the determination of glycollic acid, Klenk and Uhlenbruck1 have made possible the evaluation of the amount of N-glycolloylsialic acid in isolated sialic acids. In search of a more direct method, we tried partition chromatography,

Elisabet Svennerholm; Lars Svennerholm

1958-01-01

340

Nucleic acid arrays and methods of synthesis  

DOEpatents

The present invention generally relates to high density nucleic acid arrays and methods of synthesizing nucleic acid sequences on a solid surface. Specifically, the present invention contemplates the use of stabilized nucleic acid primer sequences immobilized on solid surfaces, and circular nucleic acid sequence templates combined with the use of isothermal rolling circle amplification to thereby increase nucleic acid sequence concentrations in a sample or on an array of nucleic acid sequences.

Sabanayagam, Chandran R. (Allston, MA); Sano, Takeshi (Needham, MA); Misasi, John (Syracuse, NY); Hatch, Anson (Seattle, WA); Cantor, Charles (Del Mar, CA)

2001-01-01

341

Acidic Deposition: Sources and Ecological Effects  

Microsoft Academic Search

Acidic atmospheric deposition, popularly referred to as acid rain, is the transfer of strong acids and acid forming substances\\u000a from the atmosphere to the Earth’s surface. Acidic deposition is comprised of sulfuric and nitric acids, and ammonium derived\\u000a from atmospheric emissions of sulfur dioxide, nitrogen oxides, and ammonia respectively. These compounds are emitted by the\\u000a burning of fossil fuels and

Charles T. Driscoll; Kathy Fallon Lambert; Limin Chen

342

Seasonalepisodic control of acid deposition  

E-print Network

This report contains the climatological, technical and economic factors for episodic and seasonal control of emissions in existing power plants. Analyzing a large data set of acid deposition for the years 1982-85, we find ...

Fay, James A.

1988-01-01

343

Controlling acid rain : policy issues  

E-print Network

The policy and regulatory ramifications of U.S. acid rain control programs are examined; particularly, the alternative of a receptor-oriented strategy as constrasted to emission-oriented proposals (e.g., the Mitchell bill) ...

Fay, James A.

1983-01-01

344

Low acid producing solid propellants  

NASA Technical Reports Server (NTRS)

The potential environmental effects of the exhaust products of conventional rocket propellants have been assessed by various groups. Areas of concern have included stratospheric ozone, acid rain, toxicity, air quality and global warming. Some of the studies which have been performed on this subject have concluded that while the impacts of rocket use are extremely small, there are propellant development options which have the potential to reduce those impacts even further. This paper discusses the various solid propellant options which have been proposed as being more environmentally benign than current systems by reducing HCI emissions. These options include acid neutralized, acid scavenged, and nonchlorine propellants. An assessment of the acid reducing potential and the viability of each of these options is made, based on current information. Such an assessment is needed in order to judge whether the potential improvements justify the expenditures of developing the new propellant systems.

Bennett, Robert R.

1995-01-01

345

Molecular Structure of Abscisic acid  

NSDL National Science Digital Library

Abscisic acid (ABA) was first identified and characterized by Frederick Addicott in 1963. ABA is a naturally occurring compound in plants synthesized partially in the chloroplasts. It is a phytohormone that plays an important role in regulating transpiration, stress responses, germination of seeds and embryogenesis in plants. Abscisic acid influences most aspects of plant growth and development to some level, in part due to interactions with other phytohormones. Abscisic acid also promotes abscission of leaves and fruits, and for this reason the name abscisic is given. This plant hormone is the key factor in the adaptation of the plant to environmental stresses such as salinity, drought or water loss, and freezing temperatures. Abscisic acid promotes dormancy and helps the plant tolerate stressful conditions by suspending primary and secondary growth.

2004-11-09

346

Nitrate and Prussic Acid Poisoning  

E-print Network

Nitrate and prussic acid poisoning in cattle are noninfectious conditions that can kill livestock. This publication explains the causes and symptoms of these conditions as well as preventive measures and sampling and testing steps....

Stichler, Charles; Reagor, John C.

2001-09-05

347

Abiotic synthesis of fatty acids  

NASA Technical Reports Server (NTRS)

The formation of fatty acids by Fischer-Tropsch-type synthesis was investigated with ferric oxide, ammonium carbonate, potassium carbonate, powdered Pueblito de Allende carbonaceous chondrite, and filings from the Canyon Diablo meteorite used as catalysts. Products were separated and identified by gas chromatography and mass spectrometry. Iron oxide, Pueblito de Allende chondrite, and Canyon Diablo filings in an oxidized catalyst form yielded no fatty acids. Canyon Diablo filings heated overnight at 500 C while undergoing slow purging by deuterium produced fatty acids only when potassium carbonate was admixed; potassium carbonate alone also produced these compounds. The active catalytic combinations gave relatively high yields of aliphatic and aromatic hydrocarbons; substantial amounts of n-alkenes were almost invariably observed when fatty acids were produced; the latter were in the range C6 to C18, with maximum yield in C9 or 10.

Leach, W. W.; Nooner, D. W.; Oro, J.

1978-01-01

348

New syntheses of aminoalkylphosphonic acids  

E-print Network

. Because of the ease of formation of diethyl phosphono- acetamide (XII a) from triethyl phosphonoacetate (Vp a), this amide . was chosen for use in the initial preparation of an amino phosphonic acid by the Hofmann reaction. However, each of several.... Because of the ease of formation of diethyl phosphono- acetamide (XII a) from triethyl phosphonoacetate (Vp a), this amide . was chosen for use in the initial preparation of an amino phosphonic acid by the Hofmann reaction. However, each of several...

DeBardeleben, John Frederick

2012-06-07

349

Acid Acclimation by Helicobacter pylori  

NSDL National Science Digital Library

Helicobacter pylori is a Gram-negative neutralophile associated with peptic ulcers and gastric cancer. It has a unique ability to colonize the human stomach by acid acclimation. It uses the pH-gated urea channel, UreI, to enhance urea access to intrabacterial urease and a membrane-anchored periplasmic carbonic anhydrase to regulate periplasmic pH to ~6.1 in acidic media, whereas other neutralophiles cannot regulate periplasmic pH and thus only transit the stomach.

PhD George Sachs (VA Wadsworth Hospital Center for Ulcer Research); David L. Weeks (University of California-Los Angeles David Geffen School of Medicine); Yi Wen (University of California-Los Angeles David Geffen School of Medicine); Elizabeth A. Marcus (University of California-Los Angeles David Geffen School of Medicine); David R. Scott (University of California-Los Angeles David Geffen School of Medicine); Klaus Melchers (Altana Research Institute)

2005-12-01

350

Annual zoledronic acid for osteoporosis.  

PubMed

Zoledronic acid (Aclasta - Novartis) is the first bisphosphonate to be licensed in the UK as a once-yearly intravenous treatment for women with postmenopausal osteoporosis. Promotional materials claim that the drug "provides powerful osteoprotection with yearlong compliance", with "significant 3 year fracture reduction at all key sites". Here we consider whether zoledronic acid has a role in the treatment of women with postmenopausal osteoporosis. PMID:19056701

2008-12-01

351

BranchedChain Amino Acids  

Microsoft Academic Search

The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are synthesized by bacteria,\\u000a fungi, and plants, but are essential for vertebrates including humans, who must receive them from their\\u000a diet. The interest to construct overproducing industrial strains therefore stems from the need to supplement\\u000a the food or feed with these amino acids to use them in medical treatment and as

Miroslav Pátek

352

Molecular Structure of Glucuronic acid  

NSDL National Science Digital Library

Glucuronic acid is a substance derived from uronic acid, and is found in both plants and animals, usually in combination with phenols or alcohols. It is primarily used in detoxifying drugs and toxins to ensure easy elimination from the body. This substance is soluble in water and alcohol and has a melting point of 165 degrees Celsius. It exhibits mutarotation in the crystal form or its specific rotation of light changes depending on the way the crystals were prepared.

2003-05-08

353

Rainfall acidity in northern Britain  

Microsoft Academic Search

The acidity of rain has attracted considerable international interest during the past decade. An area of enhanced rainfall acidity with its focus in the Low Countries of north-west Europe was identified by the European air chemistry study1 for the period 1955-68, and widespread concern arose as a result of observations that fish populations were decreasing in areas of Scandinavia subject

D. Fowler; J. N. Cape; I. D. Leith; I. S. Paterson; J. W. Kinnaird; I. A. Nicholson

1982-01-01

354

Chemical composition of acid fog  

SciTech Connect

Fog water collected at three sites in Los Angeles and Bakersfield, California, was found to have higher acidity and higher concentrations of sulfate, nitrate, and ammonium than previously observed in atmospheric water droplets. The pH of the fog water was in the range of 2.2 to 4.0. the dominant processes controlling the fog water chemistry appear to be the condensation and evaporation of water vapor on preexisting aerosol and the scavenging of gas-phase nitric acid.

Waldman, J.M.; Munger, J.W.; Jacob, D.J.; Flagan, R.C.; Morgan, J.J.; Hoffmann, M.R.

1982-11-12

355

ACID HYDROLYSIS OF AZIRIDINYL PHOSPHORAMIDES  

Microsoft Academic Search

The acid hydrolysis of two model aziridinyl phosphoramides, l-aziridinylbis(dimethylamino)phosphine oxide (11) and bis(l-aziridinyl) (dimethylamino)phosphine oxide (16), in aqueous acetic acid proceeded by an initial aziridine ring opening to give 2-hydroxyethyl phosphoramides 12 and 17, respectively. These intermediates rapidly cyclized to an oxazaphospholidine ring structure 13 or 18, with the subsequent loss of dimethylamine or aziridine. Analysis of ongoing hydrolysis showed

Jerry B. Stokes; Charles W. Woods; Alexej B. Borkovec

1981-01-01

356

Radiolysis of sulfuric acid, sulfuric acid monohydrate, and sulfuric acid tetrahydrate and its relevance to Europa  

Microsoft Academic Search

We report laboratory studies on the 0.8MeV proton irradiation of ices composed of sulfuric acid (H2SO4), sulfuric acid monohydrate (H2SO4·H2O), and sulfuric acid tetrahydrate (H2SO4·4H2O) between 10 and 180K. Using infrared spectroscopy, we identify the main radiation products as H2O, SO2, (S2O3)x, H3O+, HSO4-, and SO42-. At high radiation doses, we find that H2SO4 molecules are destroyed completely and that

M. J. Loeffler; R. L. Hudson; M. H. Moore; R. W. Carlson

2011-01-01

357

Digestion and absorption of polyunsaturated fatty acids  

E-print Network

bring to light the esterification step, particularly the integration of polyunsatura- ted fatty acids. polyunsaturated fatty acid / digestion / absorption pathway / enterocyte esterification / intesti- nal lipoprotein

Boyer, Edmond

358

Acidic extracellular microenvironment and cancer.  

PubMed

Acidic extracellular pH is a major feature of tumor tissue, extracellular acidification being primarily considered to be due to lactate secretion from anaerobic glycolysis. Clinicopathological evidence shows that transporters and pumps contribute to H+ secretion, such as the Na+/H+ exchanger, the H+-lactate co-transporter, monocarboxylate transporters, and the proton pump (H+-ATPase); these may also be associated with tumor metastasis. An acidic extracellular pH not only activates secreted lysosomal enzymes that have an optimal pH in the acidic range, but induces the expression of certain genes of pro-metastatic factors through an intracellular signaling cascade that is different from hypoxia. In addition to lactate, CO2 from the pentose phosphate pathway is an alternative source of acidity, showing that hypoxia and extracellular acidity are, while being independent from each other, deeply associated with the cellular microenvironment. In this article, the importance of an acidic extracellular pH as a microenvironmental factor participating in tumor progression is reviewed. PMID:24004445

Kato, Yasumasa; Ozawa, Shigeyuki; Miyamoto, Chihiro; Maehata, Yojiro; Suzuki, Atsuko; Maeda, Toyonobu; Baba, Yuh

2013-01-01

359

Acidic extracellular microenvironment and cancer  

PubMed Central

Acidic extracellular pH is a major feature of tumor tissue, extracellular acidification being primarily considered to be due to lactate secretion from anaerobic glycolysis. Clinicopathological evidence shows that transporters and pumps contribute to H+ secretion, such as the Na+/H+ exchanger, the H+-lactate co-transporter, monocarboxylate transporters, and the proton pump (H+-ATPase); these may also be associated with tumor metastasis. An acidic extracellular pH not only activates secreted lysosomal enzymes that have an optimal pH in the acidic range, but induces the expression of certain genes of pro-metastatic factors through an intracellular signaling cascade that is different from hypoxia. In addition to lactate, CO2 from the pentose phosphate pathway is an alternative source of acidity, showing that hypoxia and extracellular acidity are, while being independent from each other, deeply associated with the cellular microenvironment. In this article, the importance of an acidic extracellular pH as a microenvironmental factor participating in tumor progression is reviewed. PMID:24004445

2013-01-01

360

Magnesium and arachidonic acid metabolism.  

PubMed

The arachidonic acid content of plasma lipoproteins is altered during dietary magnesium deficiency, although the tissue arachidonic acid content seems to be unchanged. The primary event triggering these changes is probably the loss of extracellular Mg2+, as it is not clear whether dietary magnesium deficiency produces loss of intracellular Mg2+. In the isolated rabbit heart, in vitro perfusion conditions which produce loss of intracellular Mg2+ also result in disturbances of arachidonic acid metabolism. The metabolism of exogenous arachidonic acid to prostaglandins is increased without changing the Km or Vmax of cyclo-oxygenase. The incorporation of arachidonic acid into tissue phospholipids is significantly reduced, although the incorporation of oleate, stearate, and linolenate is either increased or unchanged. These data indicate that the activity of the enzymes (CoA synthetases and acyl transferases) which mediate arachidonate incorporation is reduced during Mg2+ depletion. Since protein-kinase-C-mediated phosphorylation of both CoA synthetase and acyl transferase reduces their activity, and since protein kinase C has an Mg2+ binding site, it is possible to speculate that loss of intracellular Mg2+ may lead to the activation of protein kinase C, with the consequent reduction of arachidonic acid reacylation enzyme activity. PMID:8274364

Weis, M T; Saunders, C

1993-06-01

361

Molecular Structure of Oxalic acid  

NSDL National Science Digital Library

Oxalic acid is an odorless, colorless powder or granular solid. It is used as a scouring agent in textiles for finishing, stripping, cleaning, and as a bleaching agent for stain removal. Oxalic acid is also used as a rust remover as well as a grease and wax removing agent in metal cleaning. It is also used to clean and sterilize equipment, slso as a purifying agent in the pharmaceutical industry, in the waste water treatment industry and is also used to remove calcium from water. Oxalic acid is found in many plants and in many vegetables, for example sorrel, spinach and rhubarb, usually as its calcium or potassium salts. Oxalic acid is produced commercially by nitric acid oxidation of starch. It also can be made by fusing sawdust (or other forms of cellulose) with a mixture of sodium hydroxide and potassium hydroxide. Oxalic acid may be released to the environment in tobacco smoke, automobile exhaust, rendering, in waste streams from pulp bleaching, and by photochemical oxidations of anthropogenic compounds during long range transport.

2004-11-10

362

A Study of the Acid Properties of Structurally and Compositionally Different Heteropoly Acids in Acetic Acid  

Microsoft Academic Search

The acid properties of heteropoly acids of the following three structure types were studied by conductometry in acetic acid: Keggin (H3PW12O40, H3PMo12O40, H4SiW12O40, H3PW11ThO39; and H5PW11XO40, where X(IV) = Ti or Zr), Dawson (a-H6P2W18O62and a-H6P2Mo18O62), and H6P2W21O71(H2O)3. These compounds are electrolytes that dissociate in only the first step of this solvent. The thermodynamic dissociation constants of the heteropoly acids were

M. N. Timofeeva; M. M. Matrosova; G. M. Maksimov; V. A. Likholobov

2001-01-01

363

Polypyrrole based strong acid catalyst for acetalization  

NASA Astrophysics Data System (ADS)

Novel polypyrrole based acid catalyst has been synthesized through the neutralization reaction of polypyrrole and sulfuric acid. The polypyrrole based acid owned the acidity as high as 6.0 mmol/g, which was much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the novel solid acid were investigated through the acetalization. The results showed that the novel solid acid held high activities for the reactions. Furthermore, the recycled activities of the catalyst indicated that the solid acid owned high stability during the catalytic process and little acid sites dropped from polypyrrole. The high acidity and stability made the novel polypyrrole based acid hold great potential for the green chemical processes.

Liang, Xuezheng; Cheng, Yuxiao; Qi, Chenze

2011-09-01

364

Bile acids: regulation of apoptosis by ursodeoxycholic acid  

PubMed Central

Bile acids are a group of molecular species of acidic steroids with peculiar physical-chemical and biological characteristics. At high concentrations they become toxic to mammalian cells, and their presence is pertinent in the pathogenesis of several liver diseases and colon cancer. Bile acid cytoxicity has been related to membrane damage, but also to nondetergent effects, such as oxidative stress and apoptosis. Strikingly, hydrophilic ursodeoxycholic acid (UDCA), and its taurine-conjugated form (TUDCA), show profound cytoprotective properties. Indeed, these molecules have been described as potent inhibitors of classic pathways of apoptosis, although their precise mode of action remains to be clarified. UDCA, originally used for cholesterol gallstone dissolution, is currently considered the first choice therapy for several forms of cholestatic syndromes. However, the beneficial effects of both UDCA and TUDCA have been tested in other experimental pathological conditions with deregulated levels of apoptosis, including neurological disorders, such as Alzheimer's, Parkinson's, and Huntington's diseases. Here, we review the role of bile acids in modulating the apoptosis process, emphasizing the anti-apoptotic effects of UDCA and TUDCA, as well as their potential use as novel and alternate therapeutic agents for the treatment of apoptosis-related diseases. PMID:19417220

Amaral, Joana D.; Viana, Ricardo J. S.; Ramalho, Rita M.; Steer, Clifford J.; Rodrigues, Cecilia M. P.

2009-01-01

365

Fatty Acids, Antibiotic Resistance, and Deoxyribonucleic Acid Homology Groups of Bradyrhizobiurn japonicum  

Microsoft Academic Search

The fatty acid compositions and multiple antibiotic resistance patterns of 32 strains of Bradyrhizobium japonicum correlated with two major deoxyribonucleic acid homology groups. In group I, the fatty acid composition was 1.3% 16:l cis9 acid, 3.6% 16:lC acid, 8.8% 16:O acid, 1.2% 19:0 cyclopropane acid, and 81.2% 18:l acid. Group I1 contained 0.5% 16:lC acid, 11.1% 16:O acid, 0.8% 17:O

L. D. KUYKENDALL; M. A. ROY; J. J. O'NEILL

366

Kinetic and safety assessment for salicylic acid nitration by nitric acid/acetic acid system.  

PubMed

The nitration process of salicylic acid for the production of the important intermediate 5-nitrosalicylic acid is studied from thermokinetic and safety points of view. Investigations carried out by considering, as process deviations, the loss of the thermal control point out the possibility of runaway phenomena due to the occurrence of polynitration reactions. Isothermal experiments are carried out in various conditions to assess the involved reaction network and reaction kinetics. PMID:16343755

Andreozzi, R; Caprio, V; Di Somma, I; Sanchirico, R

2006-06-30

367

Dietary Eicosapentaenoic Acid and Docosahexaenoic Acid Are More Effective than Alpha-Linolenic Acid in Improving Insulin Sensitivity in Rats  

Microsoft Academic Search

In the present study, we investigated whether long-term administration of high dose of ?-linolenic acid (ALA) is able to mimic the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) or a mixture of both with respect to insulin sensitivity in male Wistar rats. Furthermore, we intended to test whether these n–3 polyunsaturated fatty acids reveal differential effects on glucose

Gaby Andersen; Kerstin Harnack; Helmut F. Erbersdobler; Veronika Somoza

2008-01-01

368

Chloro- and bromoacetates in natural archives of firn from Antarctica  

SciTech Connect

A firn core was drilled in Dronning Maud Land, Antarctica, to investigate the presence of haloacetates in snow that had accumulated over the past 200 years. By employing GC-MS detection of methyl esters of haloacetic acids, the authors were able to measure haloacetate concentrations down to one or a few nanograms per liter. Trichloroacetate (TCA) and dibromoacetate (DBA) were found in firn at concentrations that clearly exceeded the blank level of the applied analytical procedure, with mean concentrations estimated to 12 and 6 ng/L, respectively. There were also indications that mono- and dichloroacetate (MCA and DCA) were present in firn, whereas monobromoacetate (MBA) was found only in samples of surficial snow. The authors concluded that there is a significant natural background level of TCA and DBA in precipitation based on the following: (i) several of samples represented snow accumulated in the 19th century; (ii) haloacetates can be expected to be immobile in Antarctic firn; (iii) extensive measures were taken to prevent sample contamination; and (iv) blank levels of the analytical procedure used were low and stable. In addition, their results suggested that MCA and DCA also occur naturally in precipitation.

Sydow, L.M. von; Nielsen, A.T.; Grimvall, A.B.; Boren, H.B.

2000-01-15

369

Gallic Acid, Ellagic Acid and Pyrogallol Reaction with Metallic Iron  

NASA Astrophysics Data System (ADS)

The reaction between gallic acid, ellagic acid and pyrogallol with metallic iron was studied using infrared and Mössbauer spectroscopy. Most hydrolysable tannins with interesting anticorrosive or inhibition properties are structurally related to these compounds, thus they may be used as models for the study of hydrolysable tannins and related polyphenols. The interaction was followed up to 3 months. Results indicated two different behaviors. At polyphenol concentrations higher than 1% iron converts to sparingly soluble and amorphous ferric (and ferrous) polyphenolate complexes. At lower concentrations (0.1%), the hydrolysis reactions are dominant, resulting in the formation of oxyhydroxides, which can be further reduced to compounds like magnetite by the polyphenols.

Jaén, J. A.; González, L.; Vargas, A.; Olave, G.

2003-06-01

370

Biopharmaceutical aspects of tolfenamic acid.  

PubMed

The pharmacokinetics of tolfenamic acid is well described by a two-compartment model with relatively short half-lives (T/2 beta 1-2 hours) and tolfenamic acid is highly protein-bound with small volumes of distribution. It is cleared relatively fast (150-200 ml/min), mainly by hepatic metabolism and the metabolites are renally cleared as glucuronic acid conjugates. The peroral absorption is good and the peroral bioavailability is about 75%, as first pass metabolism accounts for about 20%. Tolfenamic acid shows linear pharmacokinetics and during multiple dosage regimen, i.e. thrice daily, no accumulation beyond the second dose is observed. The bioavailability in dependence of age and disease has been studied and only in the case of severe liver or kidney impairment, a change in dosage regimen seems warranted. The development of different formulations will be outlined, mainly on rectal delivery, on sustained release and rapid release oral formulations, on topical ointment, and on parenteral delivery. The problems with tolfenamic acid in pharmaceutical formulation caused mainly by poor solubility will be discussed. Formulations ready for the market now or very soon are Clotam capsules (tablets). Clotam retard tablets, Clotam suppositories, and Clotam oral suspension, whereas rapid tablets, topical ointments, and parenteral formulations need further development to be ready for marketing in the years to come. PMID:7816776

Pedersen, S B

1994-01-01

371

Identifying acid salts of magnesium  

SciTech Connect

In preliminary work they found that significant quantities of certain nitrogen oxides and of sulfuric acid were absorbed by lower hydrates of magnesium sulfate. It appeared that acid salts were being formed but the known chemistry of group IIA (group 2) sulfates and acid sulfates which was worked out many years ago did not provide an explanation of their observations. They developed a new technique for delineating the solidus boundary of ternary mixtures using friability tests and applied it to the systems of interest. Magnesium acid salt hydrates with compositions on the solidus boundary could be readily identified. X-ray powder patterns confirmed the existence of two previously unknown ternary compounds, Mg/sub 2/(HSO/sub 4/)/sub 2/SO/sub 4/ x 4H/sub 2/O and Mg(HSO/sub 4/)/sub 2/ x H/sub 2/SO/sub 4/ x 3H/sub 2/O. Mixed acid sulfate-nitrate-hydrates could be detected but fuming at room temperatures interfered with quantitative determinations of the solidus boundary and X-ray measurements.

Plumb, R.; Thivierge, R.F. Jr.; Xu, W.W.

1987-11-05

372

Original article Concentrations of catecholamines, ascorbic acid,  

E-print Network

Original article Concentrations of catecholamines, ascorbic acid, progesterone and oxytocin progesterone, oxytocin (OT), dopamine (DA), noradrenaline (NA) and ascorbic acid, these compounds were measured-cold metaphosphoric acid (for ascorbic acid). There were no signi- ficant differences in the measured parameters

Paris-Sud XI, Université de

373

Original article Antimicrobial activity of fatty acids  

E-print Network

. For example, while myr- istic acid (14:0) was only slightly active (10 mm inhibition zone), myristoleic acidOriginal article Antimicrobial activity of fatty acids against Bacillus larvae, the causative agent and unsaturated free fatty acids were tested for their antibiotic activ- ity against Bacillus larvae

Paris-Sud XI, Université de

374

Acid Rain: Effects on Fish and Wildlife.  

National Technical Information Service (NTIS)

This report discusses: What is acid rain; What causes acid rain; Where do sulfur and nitrogen oxides originate; What areas in the U.S. are susceptible to acid rain; Are there early warning signals of acidification to aquatic resources; How does acid rain ...

K. S. Mayer, E. P. Multer, R. K. Schreiber

1984-01-01

375

Acid sorption regeneration process using carbon dioxide  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

King, C. Judson (Kensington, CA); Husson, Scott M. (Anderson, SC)

2001-01-01

376

Extraction of carboxylic acids by amine extractants  

Microsoft Academic Search

This work examines the chemistry of solvent extraction by long-chain amines for recovery of carboxylic acids from dilute aqueous solution. Long-chain amines act as complexing agents with the acid, which facilitates distribution of the acid into the organic phase. The complexation is reversible, allowing for recovery of the acid from the organic phase and regeneration of the extractant. Batch extraction

Janet Ayako Tamada; C. J. King

1989-01-01

377

21 CFR 189.155 - Monochloroacetic acid.  

...2014-04-01 2014-04-01 false Monochloroacetic acid. 189.155 Section 189.155 Food and Drugs...Use as Human Food § 189.155 Monochloroacetic acid. (a) Monochloroacetic acid is the chemical chloroacetic acid, C2 H3...

2014-04-01

378

21 CFR 184.1021 - Benzoic acid.  

... 2014-04-01 2014-04-01 false Benzoic acid. 184.1021 Section 184.1021 Food and Drugs...Substances Affirmed as GRAS § 184.1021 Benzoic acid. (a) Benzoic acid is the chemical benzenecarboxylic acid (C7 H6...

2014-04-01

379

8, 687725, 2008 Effect of fatty acids  

E-print Network

, high contents of humic acids in the aerosol, a struc- turally inhomogeneous, quite water solubleACPD 8, 687�725, 2008 Effect of fatty acids on HNO3 uptake to aqueous aerosol K. Stemmler et al Chemistry and Physics Discussions The effect of fatty acid surfactants on the uptake of nitric acid

Paris-Sud XI, Université de

380

Salicylic acid-independent plant defence pathways  

Microsoft Academic Search

Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent

Corné M. J Pieterse; Leendert C van Loon

1999-01-01

381

Enhancers of iron absorption: ascorbic acid and other organic acids.  

PubMed

Ascorbic acid (AA), with its reducing and chelating properties, is the most efficient enhancer of non-heme iron absorption when its stability in the food vehicle is ensured. The number of studies investigating the effect of AA on ferrous sulfate absorption far outweighs that of other iron fortificants. The promotion of iron absorption in the presence of AA is more pronounced in meals containing inhibitors of iron absorption. Meals containing low to medium levels of inhibitors require the addition of AA at a molar ratio of 2:1 (e.g., 20 mg AA: 3 mg iron). To promote absorption in the presence of high levels of inhibitors, AA needs to be added at a molar ratio in excess of 4:1, which may be impractical. The effectiveness of AA in promoting absorption from less soluble compounds, such as ferrous fumarate and elemental iron, requires further investigation. The instability of AA during food processing, storage, and cooking, and the possibility of unwanted sensory changes limits the number of suitable food vehicles for AA, whether used as vitamin fortificant or as an iron enhancer. Suitable vehicles include dry-blended foods, such as complementary, precooked cereal-based infant foods, powdered milk, and other dry beverage products made for reconstitution that are packaged, stored, and prepared in a way that maximizes retention of this vitamin. The consumption of natural sources of Vitamin C (fruits and vegetables) with iron-fortified dry blended foods is also recommended. Encapsulation can mitigate some of the AA losses during processing and storage, but these interventions will also add cost. In addition, the bioavailability of encapsulated iron in the presence/absence of AA will need careful assessment in human clinical trials. The long-term effect of high AA intake on iron status may be less than predicted from single meal studies. The hypothesis that an overall increase of dietary AA intake, or fortification of some foods commonly consumed with the main meal with AA alone, may be as effective as the fortification of the same food vehicle with AA and iron, merits further investigation. This must involve the consideration of practicalities of implementation. To date, programs based on iron and AA fortification of infant formulas and cow's milk provide the strongest evidence for the efficacy of AA fortification. Present results suggest that the effect of organic acids, as measured by in vitro and in vivo methods, is dependent on the source of iron, the type and concentration of organic acid, pH, processing methods, and the food matrix. The iron absorption-enhancing effect of AA is more potent than that of other organic acids due to its ability to reduce ferric to ferrous iron. Based on the limited data available, other organic acids may only be effective at ratios of acid to iron in excess of 100 molar. This would translate into the minimum presence/addition of 1 g citric acid to a meal containing 3 mg iron. Further characterization of the effectiveness of various organic acids in promoting iron absorption is required, in particular with respect to the optimal molar ratio of organic acid to iron, and associated feasibility for food application purposes. The suggested amount of any organic acid required to produce a nutritional benefit will result in unwanted organoleptic changes in most foods, thus limiting its application to a small number of food vehicles (e.g., condiments, beverages). However, fermented foods that already contain high levels of organic acid may be suitable iron fortification vehicles. PMID:15743017

Teucher, Birgit; Olivares, Manuel; Cori, Héctor

2004-11-01

382

Acid deposition and forest decline  

SciTech Connect

The available evidence does not show a clear cause and effect relationship between acid deposition and forest decline and dieback in the US. The second of two articles examines soil and vegetation changes, summarizes the theories on spruce and fir dieback in Central Europe, and assesses the possible natural and manmade causes. The location, topography and other characteristics of the high-elevation forests of eastern North America cause them to be receptors of high levels of acid deposition and airborn trace metals. The authors find several possible pathways for acid deposition to contribute to spruce mortality, but none are supported by convincing evidence. However, there is evidence for the triggering effect of drought in a situation of multiple stresses. 55 references, 13 figures, 1 table.

Johnson, A.H.; Siccama, T.G.

1983-01-01

383

(International conference on acidic deposition)  

SciTech Connect

The traveler took the opportunity to participate in a mini-sabbatical at the Institute of Terrestrial Ecology (ITE) in Edinburgh, Scotland, as a part of planned travel to Glasgow, Scotland, to attend the International Conference on Acidic Precipitation. The purpose of the sabbatical was to provide quality time for study and interchange of ideas with scientists at ITE working on physiological effects of acidic deposition and to allocate significant time for writing and synthesizing of results of physiological studies from the National Forest Response Program's Spruce/Fir Research Cooperative. The study focused on the very significant cytological and physiological effects of calcium deficiency in trees, a response that appears to be amplified in spruce by acidic deposition.

McLaughlin, S.B. Jr.

1990-10-05

384

Hydroxamic Acids in Asymmetric Synthesis  

PubMed Central

Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst’s center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Due to their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless Asymmetric Epoxidation, which uses titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless Asymmetric Epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities. PMID:23157425

Li, Zhi; Yamamoto, Hisashi

2012-01-01

385

Molecular Structure of Oleic acid  

NSDL National Science Digital Library

A mono-unsaturated fatty acid, oleic acid is a component of almost all natural fats. It is obtained from any of various vegetable and animal oils and fats, particularly the seeds of castor, sunflower, safflower, parsley, soybean, flax, perilla, and celery. A colorless or yellow-to-red oily liquid with a lard-like odor, it solidifies to a crystalline mass at four degrees Celsius. When exposed to air it oxidizes and acquires a yellow to brown color and rancid odor; for this reason it should be kept sealed in a container and away from sunlight. It is almost completely insoluble in water but is soluble in alcohol, benzene chloroform, ether, and fixed and volatile oils. Although oleic acid has a low level of toxicity when absorbed orally, it is mildly irritating to the skin and mucous membranes. It also is combustible. Oleic acid is used as a soap base and in the production of food-grade additives, ointments, cosmetics, fragrance products, polishing compounds, surface coatings, and manufacturing driers. It is used for waterproofing textiles and for thickening lubricating oils. It also is used as a solvent in the manufacture of pharmaceuticals. It contributes to the flavor of foods and is found in sweet cider apples. One of the "good" or unsaturated fatty acids, oleic acid has proven helpful to cell and heart function. It has shown anti-inflammatory effects in the body and has been used to treat arthritis, asthma, allergies, and skin conditions. Its inclusion in the diet has improved cases of diabetes, depression, menopausal problems, obesity, memory and learning disabilities, eye problems, and digestive disorders. It is considered to lower the incidence of cancer (as an antioxidant), multiple sclerosis, and lupus as well.

2003-05-08

386

New Insights into Bile Acid Malabsorption  

Microsoft Academic Search

Bile acid malabsorption occurs when there is impaired absorption of bile acids in the terminal ileum, so interrupting the\\u000a normal enterohepatic circulation. The excess bile acids in the colon cause diarrhea, and treatment with bile acid sequestrants\\u000a is beneficial. The condition can be diagnosed with difficulty by measuring fecal bile acids, or more easily by retention of\\u000a selenohomocholyltaurine (SeHCAT), where

Ian Johnston; Jonathan Nolan; Sanjeev S. Pattni; Julian R. F. Walters

387

Inhibitors of Fatty Acid Synthesis and Elongation  

NSDL National Science Digital Library

Fatty acid synthesis and fatty acid elongation are two parts of a critically important pathway in plants. The endproducts are essential components of cell membranes, waxes, and suberin. Two chemical families of herbicide (groups that share similar chemical structures) inhibit fatty acid synthesis, while fatty acid elongation is inhibited by two other families. This lesson will provide an overview of fatty acid synthesis and elongation, and explain where herbicides inhibit the pathway. Mechanisms of resistance to these herbicides will be described.

388

Structure of beta-Boswellinic Acid  

Microsoft Academic Search

THE investigations of Ruzicka, and of Winterstein and their co-workers, have shown that the majority of the triterpene acids (hederagenin, gypsogenin, oleanolic acid, sia- and suma-resinolic acids) are in all probability theta-hydroxy-gamma : delta-unsaturated mono-basic acids, as indicated in the accompanying formula1. On the other hand, (beta-boswellinic acid, C29H46(OH)COOH, one of the principal triterpene constituents of frankincense, evidently possesses a

J. C. E. Simpson

1937-01-01

389

Recovery of Carboxylic Acids from Fermentation Broth via Acid Springing  

E-print Network

ix LIST OF FIGURES FIGURE Page 1-1 Oil consumption of the United States and other countries ......................... 1 1-2... MixAlco process overview ......................................................................... 5 1-3 Acid springing process .............................................................................. 7 2-1 Projected dimensions of 0...

Dong, Jipeng

2010-01-14

390

Acid soil and acid rain, 2nd edition  

Microsoft Academic Search

This book examines the basic chemical processes involved in acidification in order to better assess their long-term effects on the status of soils, the health of plants and other living species that depend on them. It also discusses acidity, pH and protons their significance in bioenergetics and the consequent role of autotrophic organisms in acidifying ecosystems. This edition incorporates and

1992-01-01

391

Amino Acid-Derived Enaminones  

PubMed Central

A new reaction for the preparation of enaminones has been discovered. This method employs ?-amino acids as starting materials to allow diversification as well as incorporation of chirality. The ?-amino acids, once converted to ynones, are readily cyclized to the desired six membered enaminone via a two-step, one pot protocol. Although disguised as a 6-endo-dig cyclization, the reagents employed in the transformation play a direct role in bond making and bond breaking, thus changing the mode of addition. PMID:16819843

Turunen, Brandon J.; Georg, Gunda I.

2008-01-01

392

Molecular Structure of (+-)-Malic acid  

NSDL National Science Digital Library

Malate, or Malic acid, is found readily in fruits and in the leaves of C4 and CAM plants as storage for carbon dioxide (CO2). In C4 plants, malate is an intermediate during photosynthesis, while in CAM plants it is used to store the CO2 until the stomata are closed at night. It is also key to the production of ATP by the mitochondria. Oxaloacetate is reduced to malate, which is then transported into the mitochondria. Malic acid is frequently used for flavoring of an assortment of products. It is also used as a drug to assist ATP formation, ensuring proper muscle function at even low oxygen levels.

2003-05-08

393

Benefits of acid rain controls  

SciTech Connect

The acid rain debate has been distorted by a mistaken political paradigm. This paradigm holds that acid rain controls will benefit only a few lakes and streams, mostly in the Adirondack Mountains in northeastern New York State. It holds that the costs of a control program will fall on the Midwest but that none of the benefits will occur there since no sensitive lakes and streams are found in that area. The author discussed this problem and pointed out that sulfur dioxide was responsible for several types of pollution damage and that all the states would benefit from the reduction of sulfur dioxide emissions.

Hawkins, D.G.

1984-04-01

394

Bipolar lead acid battery development  

NASA Technical Reports Server (NTRS)

A modular bipolar battery configuration is under development at Johnson Control, Inc. (JCI) and the Jet Propulsion Laboratory (JPL). The battery design, incorporating proven lead acid electrochemistry, yields a rechargeable, high-power source that is light weight and compact. This configuration offers advantages in power capability, weight, and volume over conventional monopolar batteries and other battery chemistries. The lead acid bipolar battery operates in a sealed, maintenance-free mode allowing for maximum application flexibility. It is ideal for high-voltage and high-power applications.

Eskra, Michael; Vidas, Robin; Miles, Ronald; Halpert, Gerald; Attia, Alan; Perrone, David

1991-01-01

395

Selective Catalysis of Lactic Acid to Produce Commodity Chemicals  

Microsoft Academic Search

Owning to its biobased organic acid, low cost and multiple reactive functionalities as it contains both one carboxylic acid group and hydroxyl group, lactic acid has been described as a commodity chemical sleeping giant. In this review, the conversion of lactic acid to other important commodity chemicals, such as, poly L?lactic acid, acrylic acid, 2, 3?pentanedione, pyruvic acid, propanoic acid,

Yongxian Fan; Chunhui Zhou; Xiaohong Zhu

2009-01-01

396

Comparative fatty acid composition of four Sargassum species (Fucales, Phaeophyta)  

NASA Astrophysics Data System (ADS)

Fatty acid composition of four Sargassum species from Qingdao and Shidao, Shandong Province was investigated. 16:0 (palmitic acid) was the major saturated fatty acid. C18 and C20 were the main polyunsaturated fatty acids (PUFAs). Arachidonic acid and eicosapentaenoic acid predominated among polyenoic acids in all the algal species examined, except for Sargassum sp. which had low concentration of eicosapentaenoic acid.

Wu, Xiang-Chun; Lu, Bao-Ren; Tseng, C. K.

1995-12-01

397

Studies on technetium and some carboxylic and hydroxamic acids  

Microsoft Academic Search

Interactions between technetium and salicylic acid, oxalic acid, gentisic acid, dipicolinic acid, pyridine-2,5-dicarboxylic acid, salicylhydroxamic acid, dipicolindihydroxamic acid and 5-methoxycarbonyl-2-pyridinehydroxamic acid are described. The complexation reactions have been investigated (pH, , stability, stoichiometry) and the results obtained have been comparatively evaluated.

F. Grases; G. Far; J. G. March

1985-01-01

398

Citric Acid Passivation of Stainless Steel  

NASA Technical Reports Server (NTRS)

Passivation is a process for cleaning and providing corrosion protection for stainless steel. Currently, on Kennedy Space Center (KSC), only parts passivated with nitric acid are acceptable for use. KSC disposes of approximately 125gal of concentrated nitric acid per year, and receives many parts from vendors who must also dispose of used nitric acid. Unfortunately, nitric acid presents health and environmental hazards. As a result, several recent industry studies have examined citric acid as an alternative. Implementing a citric acid-based passivation procedure would improve the health and environmental safety aspects of passivation process. However although there is a lack of published studies that conclusively prove citric acid is a technically sound passivation agent. In 2007, NASA's KSC Materials Advisory Working Group requested the evaluation of citric acid in place of nitric acid for passivation of parts at KSC. United Space Alliance Materials & Processes engineers have developed a three-phase test plan to evaluate citric acid as an alternative to nitric acid on three stainless steels commonly used at KSC: UNS S30400, S41000, and S17400. Phases 1 and 2 will produce an optimized citric acid treatment based on results from atmospheric exposure at NASA's Beach Corrosion Facility. Phase 3 will compare the optimized solution(s) with nitric acid treatments. If the results indicate that citric acid passivates as well or better than nitric acid, NASA intends to approve this method for parts used at the Kennedy Space Center.

Yasensky, David; Reali, John; Larson, Chris; Carl, Chad

2009-01-01

399

Amino Acid Analyses of Acid Hydrolysates in Desert Varnish  

NASA Technical Reports Server (NTRS)

There has long been a debate as to whether rock varnish deposits are microbially mediated or are deposited by inorganic processes. Varnished rocks are found throughout the world primarily in arid and semi-arid regions. The varnish coats are typically up to 200 microns thick and are composed of clays and alternating layers enriched in manganese and iron oxides. The individual layers range in thickness from 1 micron to greater than 10 microns and may continue laterally for more than a 100 microns. Overlapping botryoidal structures are visible in thin section and scanning electron micrographs. The coatings also include small amounts of organic mater and detrital grains. Amino-acid hydrolysates offer a means of assessing the organic composition of rock varnish collected from the Sonoran Desert, near Phoenix, AZ. Chromatographic analyses of hydrolysates from powdered samples of rock varnish suggest that the interior of rock varnish is relatively enriched in amino acids and specifically in d-alanine and glutamic acid. Peptidoglycan (murein) is the main structural component of gram-positive bacterial cell walls. The d-enantiomer of alanine and glutamic acid are specific to peptidoglycan and are consequently an indicator for the presence of bacteria. D-alanine is also found in teichoic acid which is only found in gram-positive bacteria. Several researchers have cultured bacteria from the surface of rock varnish and most have been gram-positive, suggesting that gram-positive bacteria are intimately associated with varnish coatings and may play a role in the formation of varnish coatings.

Perry, Randall S.; Staley, James T.; Dworkin, Jason P.; Engel, Mike

2001-01-01

400

Pakistan Vet. J., 24(3): 2004 EFFECTS OF ASCORBIC ACID AND ACETYLSALICYLIC ACID  

E-print Network

Pakistan Vet. J., 24(3): 2004 109 EFFECTS OF ASCORBIC ACID AND ACETYLSALICYLIC ACID SUPPLEMENTATION into 5 equal groups and kept under elevated temperature (93-97o F) to see the effect of ascorbic acid, thymus and spleen to body weight of the birds. Ascorbic acid and acetylsalicylic acid supplementation

Paris-Sud XI, Université de

401

Method for production of petroselinic acid and OMEGA12 hexadecanoic acid in transgenic plants  

DOEpatents

The present invention relates to a process for producing lipids containing the fatty acid petroselinic acid in plants. The production of petroselinic acid is accomplished by genetically transforming plants which do not normally accumulate petroselinic acid with a gene for a .omega.12 desaturase from another species which does normally accumulate petroselinic acid.

Ohlrogge, John B. (Okemos, MI); Cahoon, Edgar B. (Lansing, MI); Shanklin, John (Upton, NY); Somerville, Christopher R. (Okemos, MI)

1995-01-01

402

Acid deposition in Maryland: Implications of the results of the National Acid Precipitation Assessment Program  

SciTech Connect

Acid deposition, commonly referred to as 'acid rain,' is a major global environmental concern. Acid deposition has reportedly resulted in damage to aquatic, terrestrial, and physical resources and has potentially adverse effects on human health. A component of the Maryland acid deposition program is the preparation of an annual report that summarizes yearly activities and costs of ongoing acid deposition research and monitoring programs.

DeMuro, J.; Bowmann, M.; Ross, J.; Blundell, C.; Price, R.

1991-07-01

403

Method for production of petroselinic acid and OMEGA12 hexadecanoic acid in transgenic plants  

DOEpatents

The present invention relates to a process for producing lipids containing the fatty acid, petroselinic acid, in plants. The production of petroselinic acid is accomplished by genetically transforming plants which do not normally accumulate petroselinic acid with a gene for a {omega}12 desaturase from another species which does normally accumulate petroselinic acid. 19 figs.

Ohlrogge, J.B.; Cahoon, E.B.; Shanklin, J.; Somerville, C.R.

1995-07-04

404

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria  

Microsoft Academic Search

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Ga. europaeus exhibited the highest resistance to acetic acid (10%), whereas Ga. intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal

Janja Trcek; Hirohide Toyama; Jerzy Czuba; Anna Misiewicz; Kazunobu Matsushita

2006-01-01

405

in amino-acid concentration enhanced amino-acid and glucose utilization for lipogenesis, with no  

E-print Network

in amino-acid concentration enhanced amino- acid and glucose utilization for lipogenesis more strongly amino-acid and glucose incorporation into cellular lipids, the glu- cose incorporation showed a synergistic effect between insulin and amino acids for up to 1.59 g/I amino acid in the medium

Boyer, Edmond

406

Process for the reclamation of battery acid and fluid from expended lead-acid batteries  

Microsoft Academic Search

This patent describes a method for recycling contaminated sulfuric acid from lead acid batteries to reclaimed sulfuric acid fore reuse in the batteries by removing contaminating iron impurities. It comprises: diluting the contaminated sulfuric acid to a concentration between 150 and 230 grams per liter; filtering the sulfuric acid through a first filter means to remove solid impurities.

1990-01-01

407

21 CFR 172.350 - Fumaric acid and salts of fumaric acid.  

... 2014-04-01 2014-04-01 false Fumaric acid and salts of fumaric acid. 172.350 Section 172.350 Food and Drugs...and Nutritional Additives § 172.350 Fumaric acid and salts of fumaric acid. Fumaric acid...

2014-04-01

408

Effect of formic acid and benzoic acid esters on grass preservation  

E-print Network

alternatives for benzoic acid and propionic acid was the high prices of these components. The esters of benzoicEffect of formic acid and benzoic acid esters on grass preservation A Rauramaa A Tommila J Ltd, Espoo Reseach Centre, PO Box 44, 02271 Espoo, Finland Formic acid is known to improve silage

Paris-Sud XI, Université de

409

Influence of dietary essential fatty acid level on fatty acid composition in peripheral nerve and muscle  

E-print Network

fatty acids, in the presence of a very high linoleic acid level, the PUFA of the (n-6) series decreased of polyunsaturated fatty acids (Kishimoto et al., 1969). This observation may be related to the highly specializedInfluence of dietary essential fatty acid level on fatty acid composition in peripheral nerve

Paris-Sud XI, Université de

410

Effect of Acetic Acid on the Oxidation of Ascorbic Acid in Fruits and Vegetables  

Microsoft Academic Search

IT has been established by earlier investigators that acetic acid has a destructive effect on the ascorbic acid in raw cabbage. This effect is somewhat surprising, since the lower the pH in the medium, the more stable is the ascorbic acid and, therefore, one would expect the acetic acid to have a preservative effect on the ascorbic acid in cabbage.

F. Alm

1952-01-01

411

Gadolinium-Diethylenetriamine pentaacetic acid-poly(lactic-co-glycolic acid) microbubbles  

E-print Network

Gadolinium-Diethylenetriamine pentaacetic acid-poly(lactic-co- glycolic acid) microbubbles [Gd-Diethylenetriamine pentaacetic acid-poly(lactic-co-glycolic acid) microbubbles Abbreviated name: Gd-DTPA-PLGA, Gd-PLGA SynonymImagingandContrastAgentDatabase(MICAD) #12;drug and gene delivery (7). Ao et al. (8) used poly(lactic-co-glycolic acid) (PLGA

Levin, Judith G.

412

CHAPTER 13. ACID RAIN Acid rain was discovered in the 19th century by Robert Angus  

E-print Network

decline of fish populations in the lakes of southern Norway and traced the problem to acid rain. Similar to the precipitation acidity. Both are strong acids which dissociate quantitatively in water to release H+: (R5) (R6247 CHAPTER 13. ACID RAIN Acid rain was discovered in the 19th century by Robert Angus Smith

Jacob, Daniel J.

413

The Arabidopsis hrl1 mutation reveals novel overlapping roles for salicylic acid, jasmonic acid and ethylene  

E-print Network

The Arabidopsis hrl1 mutation reveals novel overlapping roles for salicylic acid, jasmonic acid molecules: salicylic acid (SA), jasmonic acid (JA) and ethylene (ET). The hrl1 (hypersensitive response defence. Salicylic acid (SA) is both essential and suf®cient to induce SAR because transgenic expression

Raina, Ramesh

414

Role of Salicylic Acid and Fatty Acid Desaturation Pathways in ssi2-Mediated Signaling1[W  

E-print Network

Role of Salicylic Acid and Fatty Acid Desaturation Pathways in ssi2-Mediated Signaling1[W] Pradeep for the regu- lation of salicylic acid (SA)- and jasmonic acid-mediated defense signaling in the plant, including the pathogenesis-related (PR) genes and the accumulation of salicylic acid (SA) in the inoculated

Kachroo, Pradeep

415

Vinyl Citrates from Citric Acid as New Monomers.  

National Technical Information Service (NTIS)

The synthesis of citric acid vinyl esters and its homo and copolymerization properties were studied. Citric acid trivinyl ester cannot be built up directly with citric acid. Acetyl anhydro citric acid obtained by acetylation of citric acid can be converte...

H. F. Muisers, F. Mietzsch

1983-01-01

416

Process for forming sulfuric acid  

DOEpatents

An improved electrode is disclosed for the anode in a sulfur cycle hydrogen generation process where sulfur dioxie is oxidized to form sulfuric acid at the anode. The active compound in the electrode is palladium, palladium oxide, an alloy of palladium, or a mixture thereof. The active compound may be deposited on a porous, stable, conductive substrate.

Lu, Wen-Tong P. (Upper St. Clair, PA)

1981-01-01

417

Acid rain: Rhetoric and reality  

Microsoft Academic Search

Acid rain is now one of the most serious environmental problems in developed countries. Emissions and fallout were previously extremely localized, but since the introduction of tall stacks policies in both Britain and the US - pardoxically to disperse particulate pollutants and hence reduce local damage - emissions are now lifted into the upper air currents and carried long distances

1987-01-01

418

Acid Rain: A Global Perspective.  

ERIC Educational Resources Information Center

Analyzes the nature, extent, consequences, and sources of problems associated with acid precipitation. Explains the dilemma in specific countries with an emphasis on Eurasia, India, and the Artic. Discusses control options and international efforts to abate acidification in the environment. (ML)

Baldwin, John H.

1985-01-01

419

Boric Acid in Kjeldahl Analysis  

ERIC Educational Resources Information Center

The use of boric acid in the Kjeldahl determination of nitrogen is a variant of the original method widely applied in many laboratories all over the world. Its use is recommended by control organizations such as ISO, IDF, and EPA because it yields reliable and accurate results. However, the chemical principles the method is based on are not…

Cruz, Gregorio

2013-01-01

420

Acid Rain 2000±1000  

Microsoft Academic Search

This essay will be not so much concerned with temporal changes in acid rain as the intellectual thinking that has surrounded it. The span of this interest will extend from the historic past to an imagined future, in an account that will look at the origins of ideas and potential futures within a number of themes rather attempt a linear

P. Brimblecombe

2001-01-01

421

The Challenge of Acid Rain  

Microsoft Academic Search

Acid rain's effects in soil and water leave no doubt about the need to control its causes. The main culprits are sulfur dioxide and nitrogen oxides, mainly from automobiles and power plants. This paper explains the extent of the problem in the USA. This paper also discusses environmentally and economically attractive technologies for the control of these pollutants: atmospheric fluidized

Volker A. Mohnen

1988-01-01

422

Hydrogenation using hydrides and acid  

DOEpatents

A process for the non-catalytic hydrogenation of organic compounds, which contain at least one reducible functional group, which comprises reacting the organic compound, a hydride complex, preferably a transition metal hydride complex or an organosilane, and a strong acid in a liquid phase.

Bullock, R. Morris (Wading River, NY)

1990-10-30

423

Structure of the Nucleic Acids  

Microsoft Academic Search

WE have formulated a structure for the nucleic acids which is compatible with the main features of the X-ray diagram and with the general principles of molecular structure, and which accounts satisfactorily for some of the chemical properties of the substances. The structure involves three intertwined helical polynucleotide chains. Each chain, which is formed by phosphate di-ester groups and linking

Linus Pauling; Robert B. Corey

1953-01-01

424

Lactic acid fermented vegetable juices  

Microsoft Academic Search

Fermented foods are food substrates that are invaded or overgrown by edible microorganisms whose en- zymes, particularly amylases, proteases and lipases, hy- drolyse polysaccharides, proteins and lipids to non-toxic products with flavours, aromas and textures pleasant and attractive to the human consumer (STEINKRAUS 1997). The lactic acid fermentation of vegetable products, applied as a preservation method for the production of

J. KAROVI?OVÁ; Z. KOHAJDOVÁ

425

Toxicological Characterization of Phthalic Acid  

PubMed Central

There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans. PMID:24278572

Bang, Du Yeon; Lee, In Kyung

2011-01-01

426

Biopreservation by lactic acid bacteria  

Microsoft Academic Search

Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Lactic acid bacteria have a major potential for use in biopreservation because they are safe to consume and during storage they naturally dominate the microflora of many foods. In milk, brined vegetables, many cereal products and meats with added carbohydrate,

Michael E. Stiles

1996-01-01

427

Applications of peptide nucleic acids  

Microsoft Academic Search

Several exciting new developments in the applications of the DNA mimic peptide nucleic acid (PNA) have been published recently. A possible breakthrough may have come in efforts to develop PNA into gene therapeutic drugs. In eukaryotic systems, antisense activity of PNAs (as peptide conjugates) has been reported in nerve cells and even in rats upon injection into the brain, and

Peter E Nielsen

1999-01-01

428

Nucleic Acids Molecular Biology Tools  

E-print Network

Biology and Genomics #12;Nucleic Acids Proteins Molecular Biology Tools Polymerase Chain Reaction (PCR The Central Dogma Key Enzymes: DNA Polymerase; RNA Polymerase; Ribosome; Reverse transcriptase Exercise of a DNA template into an RNA. Transcriptome: All mRNA in a cell Promoter In Prokaryotes: RNA polymerase

Qiu, Weigang

429

Microwave spectrum of salicylic acid  

NASA Astrophysics Data System (ADS)

The rotational spectra of salicylic acid and of three OD deuterated species have been investigated by free jet millimiter-wave absorption spectroscopy. Only lines of the most stable conformer, the one with an intramolecular hydrogen bond between the phenolic hydrogen and the carbonyl oxygen, have been observed. The positions of the phenolic and carboxylic hydrogens have been precisely derived.

Evangelisti, Luca; Tang, Shouyuan; Velino, Biagio; Caminati, Walther

2009-03-01

430

Sulphur, sulphur dioxide, sulphuric acid  

SciTech Connect

This book provides sizeable bibliographies of literature references accompanying each section. It also provides an appendix containing recent statistical data on sulphur and sulphuric acid production, consumption, trade and prices. Ninety-five detailed diagrams and fourty-eight high-quality photographs are also provided.

Sander, U.H.F.; Fischer, H.; Rothe, U.; Kola, R.

1984-01-01

431

ACID AEROSOL MEASUREMENT INTERCOMPARISON WORKSHOP  

EPA Science Inventory

This report documents the discussions and results of the U.S. Environmental Protection Agency's (EPA's) Acid Aerosol Measurement Method intercomparison Workshop, held April 10-11, 1991 in Research Triangle Park, NC. he workshop was designed to achieve two objectives: (1) to repor...

432

An assessment of acid fog  

SciTech Connect

Airborne particles have long been associated with adverse effects on public health, begin with the notorious air pollution disasters of several decades ago. Although H{sub 2}SO{sub 4} was identified early on as a potential causal factors during these episodes (in part because of concern for potential health effects of particle acidity per se has intensified only recently. Most of the recent aerometric research in the US on acid fog has focused on the ability of clouds and fog to deliver acidity to vegetation and ecosystems. Strong acids are characterized chemically by their pH or H{sup +} concentration. For fog, concentrations are referred to the droplet liquid content; for other (i.e., ``clear air``) aerosols, to the volume of air sampled. A useful measure of the relationship between aerosol and fog is obtained by comparing their mass concentrations on the basis of the same volume of air, by multiplying fogwater concentrations by liquid water content (LWC). This paper reviews fog measurement capability, physical properties and chemistry, and presents a simple urban airshed model which is used to simulate the evolution of fog and aerosol concentrations under urban stagnation conditions.

Lipfert, F.W.

1992-12-31

433

THE ACID RAIN NOX PROGRAM  

EPA Science Inventory

Between 350,000 and 400,000 tons of annual NOx emissions have been eliminated as a result of Phase I of the Acid Rain NOx Program. As expected. the utilities have chosen emissions averaging as the primary compliance option. This reflects that, in general, NO x reductions have ...

434

Omega-3 Fatty Acids and Pregnancy  

PubMed Central

Omega-3 fatty acids are essential fatty acids that must be consumed in the diet. Adequate consumption of omega-3 fatty acids is vitally important during pregnancy as they are critical building blocks of fetal brain and retina. Omega-3 fatty acids may also play a role in determining the length of gestation and in preventing perinatal depression. The most biologically active forms of omega-3 fatty acids are docosahexaenoic acid and eicosapentaenoic acid, which are primarily derived from marine sources such as seafood and algae. Recent surveys, however, indicate that pregnant women in the United States and in other countries eat little fish and therefore do not consume enough omega-3 fatty acids, primarily due to concern about the adverse effects of mercury and other contaminants on the developing fetus. This review discusses the benefits of omega-3 fatty acid consumption during pregnancy and provides guidelines for obstetricians advising patients. PMID:21364848

Coletta, Jaclyn M; Bell, Stacey J; Roman, Ashley S

2010-01-01

435

Crystal growth and physical characterization of picolinic acid cocrystallized with dicarboxylic acids  

NASA Astrophysics Data System (ADS)

Pharmaceutical cocrystals are multicomponent materials containing an active pharmaceutical ingredient with another component in well-defined stoichiometry within the same unit cell. Such cocrystals are important in drug design, particularly for improving physicochemical properties such as solubility, bioavailability, or chemical stability. Picolinic acid is an endogenous metabolite of tryptophan and is widely used for neuroprotective, immunological, and anti-proliferative effects within the body. In this paper we present cocrystallization experiments of a series of dicarboxylic acids, oxalic acid, succinic acid, DL-tartaric acid, pimelic acid, and phthalic acid, with picolinic acid. Characterization by FT-IR and Raman spectroscopy, DSC and TG/DTG analysis, and X-ray powder diffraction show that new compounds are formed, including a 1:1 picolinium tartrate monohydrate, a 2:1 monohydrate adduct of picolinic acid and oxalic acid, and a 2:1 picolinic acid-succinic acid monohydrate cocrystal.

Somphon, Weenawan; Haller, Kenneth J.

2013-01-01

436

Novel Fluorinated Acids for Phosphoric Acid Fuel Cells. Final Report April 1985-March 1989.  

National Technical Information Service (NTIS)

A program for the synthesis of strong fluorinated acids was successfully carried out. Many examples of acids were prepared and characterized by NMR, MS, IR and several acids and derivatives were characterized by single crystal X-ray diffraction. Electroch...

D. D. DesMarteau

1989-01-01

437

The effects of acid contact time and rock surfaces on acid fracture conductivity  

E-print Network

The conductivity created in acid fracturing is a competition between two phenomena: etching of the rock surface and weakening of the rock. This study presents experimental results of acid fracturing conductivity experiments with polymer gelled acid...

Melendez Castillo, Maria Georgina

2009-06-02

438

Formation of volatile chemicals from thermal degradation of less volatile coffee components: quinic acid, caffeic acid, and chlorogenic acid.  

PubMed

The less volatile constituents of coffee beans (quinic acid, caffeic acid, and chlorogenic acid) were roasted under a stream of nitrogen, air, or helium. The volatile degradation compounds formed were analyzed by gas chromatography and gas chromatography-mass spectrometry. Caffeic acid produced the greatest amount of total volatiles. Quinic acid and chlorogenic acid produced a greater number of volatiles under the nitrogen stream than under the air stream. These results suggest that the presence of oxygen does not play an important role in the formation of volatile compounds by the heat degradation of these chemicals. 2,5-Dimethylfuran formed in relatively large amounts (59.8-2231.0 microg/g) in the samples obtained from quinic acid and chlorogenic acid but was not found in the samples from caffeic acid. Furfuryl alcohol was found in the quinic acid (259.9 microg/g) and caffeic acid (174.4 microg/g) samples roasted under a nitrogen stream but not in the chlorogenic sample. The three acids used in the present study do not contain a nitrogen atom, yet nitrogen-containing heterocyclic compounds, pyridine, pyrrole, and pyrazines, were recovered. Phenol and its derivatives were identified in the largest quantities. The amounts of total phenols ranged from 60.6 microg/g (quinic acid under helium) to 89893.7 microg/g (caffeic acid under helium). It was proposed that phenol was formed mainly from quinic acid and that catechols were formed from caffeic acid. Formation of catechol from caffeic acid under anaerobic condition indicates that the reaction participating in catechol formation was not oxidative degradation. PMID:20405916

Moon, Joon-Kwan; Shibamoto, Takayuki

2010-05-12

439

Investigations of the origin of the furan fatty acids (F-acids)  

Microsoft Academic Search

The possible role of linoleic acid as a biogenetic precursor of the furan fatty acids (F-acids) was investigated in in vivo\\u000a experiments in the rat, using a C19 analogue of linoleic acid and gas chromatography-mass spectrometry. No evidence of incorporation of this compound into the\\u000a F-acids was found. Using an improved analysis procedure by converting F-acids into their tetrahydrofuran derivatives

Charles P. Gorst-Allmana; Volker Puchta; G. Spiteller

1988-01-01

440

Effect of carbon chain length on esterification of carboxylic acids with methanol using acid catalysis  

Microsoft Academic Search

This paper reports on an investigation into the impact of carboxylic acid chain length on the kinetics of liquid-phase acid-catalyzed esterification. Using sulfuric acid and a commercial Nafion\\/silica composite solid acid catalyst (SAC-13), initial kinetics were measured for the reactions of a series of linear chain carboxylic acids (acetic, propionic, butyric, hexanoic, and caprylic acid) with methanol at 60?°C. It

Yijun Liu; Edgar Lotero; James G. Goodwin

2006-01-01

441

Ocular acid burn due to 20% concentrated salicylic acid.  

PubMed

This is a case report of severe conjunctival and corneal epithelial defects resulting from accidental exposure to salicylic acid that was mistakenly used instead of artificial tears (eye drops). The patient was treated with tobramycin 0.3%-dexamethasone 1% 3 times a day, cyclopentolate 1% twice a day, and artificial tears 6 times a day and underwent daily examinations until the corneal and conjunctival epithelial defects resolved. The corneal and conjunctival epithelial defects slowly resolved over 14 days. Visual acuity improved to its preinjury level of 20/40 in the affected eye. No residual corneal scarring was evident. Slowly resolving corneal and conjunctival epithelial defects can occur from direct contact with salicylic acid; therefore, this medication should be packaged and labeled differently from eye drops. PMID:20954793

Shazly, Tarek A

2011-03-01

442

Lipoic acid analogs with enhanced pharmacological activity.  

PubMed

Lipoic acid (1,2-dithiolane-3-pentanoic acid) is a pharmacophore with unique antioxidant and cytoprotective properties. We synthesized a library based upon the condensation of natural and unnatural amino acids with the carboxylic acid moiety of lipoic acid. SAR studies were conducted using a cardiac ischemia-reperfusion animal model. Cytoprotective efficacy was associated with the R-enantiomer of the dithiolane. Potency of library compounds was dictated by the acidic strength of the adduct. ?-N-[(R)-1,2-dithiolane-3-pentanoyl]-L-glutamyl-L-alanine, designated CMX-2043, was chosen for further pharmacologic evaluation. PMID:24316353

Kates, Steven A; Casale, Ralph A; Baguisi, Alexander; Beeuwkes, Reinier

2014-01-01

443

Antibacterial anthranilic acid derivatives from Geijera parviflora.  

PubMed

Five anthranilic acid derivatives, a mixture I of three new compounds 11'-hexadecenoylanthranilic acid (1), 9'-hexadecenoylanthranilic acid (2), and 7'-hexadecenoylanthranilic acid (3), as well as a new compound 9,12,15-octadecatrienoylanthranilic acid (4) together with a new natural product, hexadecanoylanthranilic acid (5), were isolated from Geijera parviflora Lindl. (Rutaceae). Their structures were elucidated by extensive spectroscopic measurements, and the positions of the double bonds in compounds 1-3 of the mixture I were determined by tandem mass spectrometry employing ozone-induced dissociation. The mixture I and compound 5 showed good antibacterial activity against several Gram-positive strains. PMID:24370663

Shou, Qingyao; Banbury, Linda K; Maccarone, Alan T; Renshaw, Dane E; Mon, Htwe; Griesser, Stefani; Griesser, Hans J; Blanksby, Stephen J; Smith, Joshua E; Wohlmuth, Hans

2014-03-01

444

Gelcasting of alumina from acidic aqueous medium using acrylic acid  

Microsoft Academic Search

An aqueous gelcasting process for alumina using an acrylic acid monomer has been investigated. Concentrated aqueous alumina slurries with pH 3 were set in moulds at 80°C during 10–15 min by polymerisation of the monomer contained in it using ammonium persulphate as free-radical initiator. The green density maximum (57% TD, corrected for organic content) was obtained at ?6 wt% binder

K Prabhakaran; C Pavithran

2000-01-01

445

Quinone-Amino Acid Conjugates Targeting Leishmania Amino Acid Transporters  

PubMed Central

The aim of the present study was to investigate the feasibility of targeting Leishmania transporters via appropriately designed chemical probes. Leishmania donovani, the parasite that causes visceral leishmaniasis, is auxotrophic for arginine and lysine and has specific transporters (LdAAP3 and LdAAP7) to import these nutrients. Probes 1–15 were originated by conjugating cytotoxic quinone fragments (II and III) with amino acids (i.e. arginine and lysine) by means of an amide linkage. The toxicity of the synthesized conjugates against Leishmania extracellular (promastigotes) and intracellular (amastigotes) forms was investigated, as well their inhibition of the relevant amino acid transporters. We observed that some conjugates indeed displayed toxicity against the parasites; in particular, 7 was identified as the most potent derivative (at concentrations of 1 µg/mL and 2.5 µg/mL residual cell viability was reduced to 15% and 48% in promastigotes and amastigotes, respectively). Notably, 6, while retaining the cytotoxic activity of quinone II, displayed no toxicity against mammalian THP1 cells. Transport assays indicated that the novel conjugates inhibited transport activity of lysine, arginine and proline transporters. Furthermore, our analyses suggested that the toxic conjugates might be translocated by the transporters into the cells. The non-toxic probes that inhibited transport competed with the natural substrates for binding to the transporters without being translocated. Thus, it is likely that 6, by exploiting amino acid transporters, can selectively deliver its toxic effects to Leishmania cells. This work provides the first evidence that amino acid transporters of the human pathogen Leishmania might be modulated by small molecules, and warrants their further investigation from drug discovery and chemical biology perspectives. PMID:25254495

Lizzi, Federica; Belluti, Federica; Koren, Roni; Zilberstein, Dan; Bolognesi, Maria Laura

2014-01-01

446

Radiolysis of sulfuric acid, sulfuric acid monohydrate, and sulfuric acid tetrahydrate and its relevance to Europa  

Microsoft Academic Search

We studied stability of three acid hydrates during ion irradiation in Europa-like conditions. Using infrared spectroscopy, we identify the main radiation products as H 2 O, SO 2 , (S 2 O 3 ) x , H 3 O + , HSO 4 - , and SO 4 2 - . We find that at higher irradiation temperatures, the more

M. J. Loeffler; R. L. Hudson; M. H. Moore; R. W. Carlson

2011-01-01

447

Nucleotide Composition of Nucleic Acids of Fungi I. Ribonucleic Acids  

PubMed Central

Storck, Roger (The University of Texas, Austin). Nucleotide composition of nucleic acids from fungi. I. Ribonucleic acids. J. Bacteriol. 90:1260–1264. 1965.—The nucleotide composition of the ribonucleic acids (RNA) present in extracts of 26 species of fungi was determined. The results were analyzed, together with those in the literature. It was found that the content in moles per cent of guanine plus cytosine (GC content) varied from 44.1 to 60.5 in a distribution composed of 8 species of zygomycetes, 10 of ascomycetes, 11 of deuteromycetes, and 8 of basidiomycetes. The GC-content range and average were, respectively, 44.1 to 49.3 and 46.4 for the zygomycetes, 47.4 to 54.4 and 50.2 for the ascomycetes, 48.2 to 54.5 and 51.6 for the deuteromycetes, and 50.4 to 60.5 and 52.4 for the basidiomycetes. The GC content averaged 45.6 and ranged from 44.1 to 46.3 for four Mucor species. In addition, GC contents significantly lower than 50 were also encountered in some species of Hemiascomycetidae, suggesting that AT type RNA is not uncommon in fungi. It was proposed that the base composition of fungal RNA might have a taxonomic and phylogenetic significance. PMID:5848326

Storck, Roger

1965-01-01

448

Enantiomeric Excesses of Acid Labile Amino Acid Precursors of the Murchison Meteorite  

NASA Technical Reports Server (NTRS)

Amino acids present in carbonaceous chondrite are extracted in water in part as free compounds and in approximately equal part as acid labile precursors. On the assumption that they would be free of contamination, the precursors of two Murchison amino acids that have terrestrial occurrence, alanine and glutamic acid, have been targeted for analysis of their enantiomeric ratios. Pyroglutamic acid, the precursor of glutamic acid, was found with an L-enantiomeric excess comparable to that of the free acid, while alanine's precursor, N-acetyl alanine, appears approximately racemic. Also alpha-imino propioacetic acid, a proposed end product of alanine synthesis in the meteorite, was analyzed and found racemic.

Pizzarello, Sandra

1998-01-01

449

Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility  

NASA Technical Reports Server (NTRS)

The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

1990-01-01

450

A paradoxical teratogenic mechanism for retinoic acid.  

PubMed

Retinoic acid, an active metabolite of vitamin A, plays essential signaling roles in mammalian embryogenesis. Nevertheless, it has long been recognized that overexposure to vitamin A or retinoic acid causes widespread teratogenesis in rodents as well as humans. Although it has a short half-life, exposure to high levels of retinoic acid can disrupt development of yet-to-be formed organs, including the metanephros, the embryonic organ which normally differentiates into the mature kidney. Paradoxically, it is known that either an excess or a deficiency of retinoic acid results in similar malformations in some organs, including the mammalian kidney. Accordingly, we hypothesized that excess retinoic acid is teratogenic by inducing a longer lasting, local retinoic acid deficiency. This idea was tested in an established in vivo mouse model in which exposure to excess retinoic acid well before metanephric rudiments exist leads to failure of kidney formation several days later. Results showed that teratogen exposure was followed by decreased levels of Raldh transcripts encoding retinoic acid-synthesizing enzymes and increased levels of Cyp26a1 and Cyp26b1 mRNAs encoding enzymes that catabolize retinoic acid. Concomitantly, there was significant reduction in retinoic acid levels in whole embryos and kidney rudiments. Restoration of retinoic acid levels by maternal supplementation with low doses of retinoic acid following the teratogenic insult rescued metanephric kidney development and abrogated several extrarenal developmental defects. This previously undescribed and unsuspected mechanism provides insight into the molecular pathway of retinoic acid-induced teratogenesis. PMID:22869719

Lee, Leo M Y; Leung, Chun-Yin; Tang, Walfred W C; Choi, Heung-Ling; Leung, Yun-Chung; McCaffery, Peter J; Wang, Chi-Chiu; Woolf, Adrian S; Shum, Alisa S W

2012-08-21

451

The influence of dietary docosahexaenoic acid and arachidonic acid on central nervous system polyunsaturated fatty acid composition  

Microsoft Academic Search

Numerous studies on perinatal long-chain polyunsaturated fatty acid nutrition have clarified the influence of dietary docosahexaenoic acid (DHA) and arachidonic acid (ARA) on central nervous system PUFA concentrations. In humans, omnivorous primates, and piglets, DHA and ARA plasma and red blood cells concentrations rise with dietary preformed DHA and ARA. Brain and retina DHA are responsive to diet while ARA

J. Thomas Brenna; Guan-Yeu Diau

2007-01-01

452

Oligomeric nucleic acids as antivirals.  

PubMed

Based on the natural functions and chemical characteristics of nucleic acids, a variety of novel synthetic drugs and tools to explore biological systems have become available in recent years. To date, a great number of antisense oligonucleotides, RNA interference-based tools, CpG?containing oligonucleotides, catalytic oligonucleotides, decoys and aptamers has been produced synthetically and applied successfully for understanding and manipulating biological processes and in clinical trials to treat a variety of diseases. Their versatility and potency make them equally suited candidates for fighting viral infections. Here, we describe the different types of nucleic acid-based antivirals, their mechanism of action, their advantages and limitations, and their future prospects. PMID:21278679

Mescalchin, Alessandra; Restle, Tobias

2011-01-01

453

Ascorbic Acid and Methylene Blue  

NSDL National Science Digital Library

The WebWare molecules of the month for May are featured in several articles in this issue. "Arsenic: Not So Evil After All?" discusses the pharmaceutical uses of methylene blue and its development as the first synthetic drug used against a specific disease. The JCE Classroom Activity "Out of the Blue" and the article "Greening the Blue Bottle" feature methylene blue and ascorbic acid as two key ingredients in the formulation of the blue bottle. You can also see a colorful example of these two molecules in action on the cover. "Sailing on the 'C': A Vitamin Titration with a Twist" describes an experiment to determine the vitamin C (ascorbic acid) content of citrus fruits and challenges students, as eighteenth-century sea captains, to decide the best fruit to take on a long voyage.

454

Acidic deposition and soil processes  

SciTech Connect

The results of the Integrated Lake-Watershed Acidification Study (ILWAS) show that the sensitivity of a watershed to surface water acidification is determined by the flow paths of water through the terrestrial system. If the water infiltrates through the soils into the groundwater system, acid neutralization occurs through weathering reactions involving minerals in the soils and till. Runoff and shallow interflow result in acid surface waters. Flow paths are determined in the ILWAS watersheds by the thickness of the glacial till. Complete neutralization can occur even in areas underlain by sensitive bedrock if the flow path through the mineral horizons is long enough. This appears to hold even in areas outside of the Adirondacks. 11 references, 5 figures.

Newton, R.M.; April, R.H.

1985-08-01

455

Fragmentation of Chitosan by Acids  

PubMed Central

Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by 1H NMR spectroscopy and elemental analysis. The kinetic data indicates that the reaction was of first order. The results of polydispersity and the DA suggest that the selected experimental conditions (temperature and concentration of acid) were appropriate to obtain the fragments having the polydispersity and the DA similar to or slightly different from those of the original one. A procedure to estimate molecular weight of fragments as well as the number of chain scissions of the fragments under the experimental conditions was also proposed. PMID:24302858

Arul, Joseph; Charlet, Gerard

2013-01-01

456

Fatty acid signalling in a mouse enteroendocrine cell line involves fatty acid aggregates rather than free fatty acids  

PubMed Central

Fatty acids induce cholecystokinin (CCK) secretion both in humans and from murine enteroendocrine cell lines. In both cases, only fatty acids above a critical acyl chain length (C10) are capable of inducing a response. Using the enteroendocrine cell line STC-1, the aim of this study was to determine whether this acyl chain length dependency is related to the fact that longer chain fatty acids are relatively insoluble in aqueous solutions and, if so, whether it is insoluble aggregates of fatty acids rather than free fatty acids which evoke CCK secretion. Solutions of fatty acids (chain length C8–C14), which were judged by filtration and Zeta sizer measurement to contain no fatty acid aggregates, never evoked CCK secretion from STC-1 cells. Filtering fatty acid solutions (of chain length C10, C12 and C14) through polytetrafluoroethylene (PTFE) filters (0.45 ?m pore size) revealed a narrow concentration range for each acid over which the amount of fatty acid removed from the solution increased sharply due to the formation of fatty acid aggregates. Filtration experiments, in which suspensions of C10, C12 and C14 fatty acids were passed through pore sizes of 0.2, 0.45 or 1.2 ?m, suggested that STC-1 cells did not respond to fatty acid aggregates of greater than 1.2 ?m, while at least 50 % of the CCK response was mediated by aggregates which were smaller than 0.45 ?m. Fatty acids induce CCK secretion from STC-1 cells by elevating intracellular Ca2+ concentration ([Ca2+]i). We therefore measured the effects on [Ca2+]i of filtered C10, C12 and C14 fatty acids. In all cases, [Ca2+]i responses were closely correlated with CCK secretion. Interestingly, while filtrates of fatty acid solutions evoked CCK secretion and elevated [Ca2+]i, freshly prepared solutions of fatty acids at the same concentration as the filtrates did not. This suggested that fatty acid aggregates were not in equilibrium with the solvent after filtration. The observation that the ability of C10, C12 and C14 filtrates to elevate [Ca2+]i decayed with time was consistent with this hypothesis. Furthermore, sonication of the filtrates abolished their ability to elevate [Ca2+]i. These data further suggest that it is a physical property of the fatty acid solution (the presence of insoluble fatty aggregates) which is responsible for the observed cellular responses. We conclude that Ca2+ mobilisation and CCK secretion in STC-1 cells is driven by a signal transduction mechanism that senses insoluble fatty acid aggregates, rather than free fatty acids in solution. PMID:11773321

Benson, R S P; Sidhu, S S; Jones, M N; Case, R M; Thompson, D G

2002-01-01

457

Acid drops are falling on the earth  

SciTech Connect

Burning of fossil fuels releases acidic oxides, which combine with water to form different acids in precipitation. Sulphur dioxide pollution is discussed in this context, with reference to Europe and north eastern North America.

Islam, S.

1981-01-01

458

Chronic boric acid poisoning in infants  

Microsoft Academic Search

We report 7 infants suffering from seizures induced by chronic boric acid ingestion. The boric acid was given by dipping a soother in a proprietary borax and honey mixture. The babies have remained well since the mixture was withheld.

K OSullivan; M Taylor

1983-01-01

459

Role of succinic acid in chemical evolution  

NASA Technical Reports Server (NTRS)

Succinic acid is converted into other carboxylic acids by ionizing radiation. The results obtained have been correlated with the ready formation of this compound in prebiotic experiments. Its role in biological systems may be related to its prebiotic occurrence.

Negron-Mendoza, A.; Ponnamperuma, C.

1982-01-01

460

Acid Precipitation in the Pacific Northwest.  

ERIC Educational Resources Information Center

Discusses the causes, sources, and problems associated with acid deposition in the Pacific Northwest. Includes a learning activity about acid rain, "Deadly Skies," which was adapted from the Project WILD Aquatic Supplement. (TW)

Baldwin, John; Kozak, David

1988-01-01

461

Replica amplification of nucleic acid arrays  

DOEpatents

A method of producing a plurality of a nucleic acid array, comprising, in order, the steps of amplifying in situ nucleic acid molecules of a first randomly-patterned, immobilized nucleic acid array comprising a heterogeneous pool of nucleic acid molecules affixed to a support, transferring at least a subset of the nucleic acid molecules produced by such amplifying to a second support, and affixing the subset so transferred to the second support to form a second randomly-patterned, immobilized nucleic acid array, wherein the nucleic acid molecules of the second array occupy positions that correspond to those of the nucleic acid molecules from which they were amplified on the first array, so that the first array serves as a template to produce a plurality, is disclosed.

Church, George M. (Brookline, MA)

2002-01-01

462

Pediatric Acid Reflux and GERD in Teens  

MedlinePLUS

... Nurses Print Share Reflux and GERD : Teen GERD Pediatric Acid Reflux and GERD in Teens If you’ ... out with your friends. There’s no reason that pediatric acid reflux disease should limit your life. GIKids ...

463

Bile acids, obesity, and the metabolic syndrome.  

PubMed

Bile acids are increasingly recognized as key regulators of systemic metabolism. While bile acids have long been known to play important and direct roles in nutrient absorption, bile acids also serve as signalling molecules. Bile acid interactions with the nuclear hormone receptor farnesoid X receptor (FXR) and the membrane receptor G-protein-coupled bile acid receptor 5 (TGR5) can regulate incretin hormone and fibroblast growth factor 19 (FGF19) secretion, cholesterol metabolism, and systemic energy expenditure. Bile acid levels and distribution are altered in type 2 diabetes and increased following bariatric procedures, in parallel with reduced body weight and improved insulin sensitivity and glycaemic control. Thus, modulation of bile acid levels and signalling, using bile acid binding resins, TGR5 agonists, and FXR agonists, may serve as a potent therapeutic approach for the treatment of obesity, type 2 diabetes, and other components of the metabolic syndrome in humans. PMID:25194176

Ma, Huijuan; Patti, Mary Elizabeth

2014-08-01

464

Research on Lead Acid Battery Electrodes.  

National Technical Information Service (NTIS)

The reactions and physical and molecular transformations that occur in lead acid battery plate active material during charge-discharge cycling have been studied under a DOE program to improve the lead acid battery for electric vehicle applications. Invest...

A. C. Simon, S. M. Caulder, C. P. Wales, R. L. Jones

1982-01-01

465

Recovery of mercury from acid waste residues  

DOEpatents

Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and then quenching the reactivity of the nitric acid prior to nitration of the mercury metal.

Greenhalgh, Wilbur O. (Richland, WA)

1989-01-01

466

Recovery of mercury from acid waste residues  

DOEpatents

Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and thence quenching the reactivity of the nitric acid prior to nitration of the mercury metal. 1 fig.

Greenhalgh, W.O.

1987-02-27

467

Hydroxylation of dehydroabietic acid by Fusarium species.  

PubMed

A novel compound, 1 beta-hydroxydehydroabietic acid has been obtained by the microbial transformation of dehydroabietic acid, using cultures of Fusarium oxysporum and F. moniliforme. Its antibacterial activity was also tested. PMID:9276983

Tapia, A A; Vallejo, M D; Gouiric, S C; Feresin, G E; Rossomando, P C; Bustos, D A

1997-09-01

468

21 CFR 582.1057 - Hydrochloric acid.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 6 2011-04-01... false Hydrochloric acid. 582.1057 Section 582.1057 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...1057 Hydrochloric acid. (a) Product....

2011-04-01

469

21 CFR 582.1057 - Hydrochloric acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01... false Hydrochloric acid. 582.1057 Section 582.1057 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...1057 Hydrochloric acid. (a) Product....

2013-04-01

470

21 CFR 582.5049 - Aminoacetic acid.  

21 Food and Drugs 6 2014-04-01... false Aminoacetic acid. 582.5049 Section 582.5049 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.5049 Aminoacetic acid. (a) Product....

2014-04-01

471

21 CFR 582.5049 - Aminoacetic acid.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 6 2012-04-01... false Aminoacetic acid. 582.5049 Section 582.5049 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.5049 Aminoacetic acid. (a) Product....

2012-04-01

472

21 CFR 582.5049 - Aminoacetic acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01... false Aminoacetic acid. 582.5049 Section 582.5049 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.5049 Aminoacetic acid. (a) Product....

2013-04-01

473

21 CFR 582.5049 - Aminoacetic acid.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 6 2010-04-01... false Aminoacetic acid. 582.5049 Section 582.5049 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.5049 Aminoacetic acid. (a) Product....

2010-04-01

474

21 CFR 582.1057 - Hydrochloric acid.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 6 2010-04-01... false Hydrochloric acid. 582.1057 Section 582.1057 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...1057 Hydrochloric acid. (a) Product....

2010-04-01

475

21 CFR 582.5049 - Aminoacetic acid.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 6 2011-04-01... false Aminoacetic acid. 582.5049 Section 582.5049 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.5049 Aminoacetic acid. (a) Product....

2011-04-01

476

21 CFR 582.1057 - Hydrochloric acid.  

21 Food and Drugs 6 2014-04-01... false Hydrochloric acid. 582.1057 Section 582.1057 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...1057 Hydrochloric acid. (a) Product....

2014-04-01

477

21 CFR 582.1057 - Hydrochloric acid.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 6 2012-04-01... false Hydrochloric acid. 582.1057 Section 582.1057 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...1057 Hydrochloric acid. (a) Product....

2012-04-01

478

TOWARD A RISK ASSESSMENT OF PERFLUOROALKYL ACIDS  

EPA Science Inventory

Perfluoroalkyl acids (PFAA) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS),and fluorotelomer alcoholsare surfactants that have wide applications in industrial and consumer products. Various fluorotelomer alcohols are known to be metabolized to perfluo...

479

Observing the Effects of Acids and Bases  

NSDL National Science Digital Library

Combining acid/base chemistry, cell biology, and quantitative research methods, this "egg-ceptional" activity promotes a truly interdisciplinary perspective. First, students find out what effect acids and bases have on calcium-based substances such as egg

Eichinger, John

2009-05-30

480

Molecular Structure of Nitric acid (aq)  

NSDL National Science Digital Library

Nitric acid was first discovered in 1648 by a German chemist, Johann Rudolf. However, in 1901 Wilhelm Ostwald developed the Ostwald Process, which became the principle way of producing nitric acid. During the Ostwald process, ammonia gas is successively oxidized to nitric oxide and nitrogen dioxide by air or oxygen in the presence of a platinum gauze catalyst. Nitric acid has a characteristic choking odor that is acrid and suffocating. It is a caustic and corrosive liquid which will attack some forms of plastics, rubber and coatings. Nitric acid is not combustible, but it may give off poisionous oxides of nitrogen and acid fumes when heated in fire. Nitric acid is mainly used in the production of fertilizers, explosives, flares and rocket propellants. Nitric acids react with toluene in the presence of sulfuric acid to form trinitrotoluene (TNT).

2002-09-10

481

Polystyrene sulphonic acid resins with enhanced acid strength via macromolecular self-assembly within confined nanospace  

NASA Astrophysics Data System (ADS)

Tightening environmental legislation is driving the chemical industries to develop efficient solid acid catalysts to replace conventional mineral acids. Polystyrene sulphonic acid resins, as some of the most important solid acid catalysts, have been widely studied. However, the influence of the morphology on their acid strength—closely related to the catalytic activity—has seldom been reported. Herein, we demonstrate that the acid strength of polystyrene sulphonic acid resins can be adjusted through their reversible morphology transformation from aggregated to swelling state, mainly driven by the formation and breakage of hydrogen bond interactions among adjacent sulphonic acid groups within the confined nanospace of hollow silica nanospheres. The hybrid solid acid catalyst demonstrates high activity and selectivity in a series of important acid-catalysed reactions. This may offer an efficient strategy to fabricate hybrid solid acid catalysts for green chemical processes.

Zhang, Xiaomin; Zhao, Yaopeng; Xu, Shutao; Yang, Yan; Liu, Jia; Wei, Yingxu; Yang, Qihua

2014-01-01

482

Multiple-acid equilibria in adsorption of carboxylic acids from dilute aqueous solution  

SciTech Connect

Equilibria were measured for adsorption of carboxylic acids from aqueous, binary-acid mixtures of lactic and succinic acids and acetic and formic acids onto basic polymeric sorbents. The experimentally determined adsorption isotherms compared well with model predictions, confirming that simple extensions from adsorption of individual acids apply. Fixed-bed studies were carried out that establish the efficacy of chromatographic fractionation of lactic and succinic acids using basic polymeric sorbents. Finally, sequential thermal and solvent regeneration of lactic and acetic acid-laden sorbents was investigated as a method to fractionate among coadsorbed volatile and nonvolatile acids. Essentially complete removal of the acetic acid from the acid-laden sorbent was achieved by vaporization under the conditions used; a small amount of loss of lactic acid (about 11%) was observed.

Husson, S.M.; King, C.J. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States)

1999-02-01

483

Chemistry of ascorbic acid radicals  

SciTech Connect

The chemistry of ascorbic acid free radicals is reviewed. Particular emphasis is placed on identification and characterization of ascorbate radicals by spectrophotometric and electron paramagnetic resonance techniques, the kinetics of formation and disappearance of ascorbate free radicals in enzymatic and nonenzymatic reactions, the effect of pH upon the spectral and kinetic properties of ascorbate anion radical, and chemical reactivity of ascorbate free radicals.

Bielski, B.H.J.

1982-01-01

484

Determinants of plasma uric acid  

Microsoft Academic Search

Obesity, alcohol consumption, and hematocrit provide an index of plasma uric acid, which in path analysis has a cultural heritability of 0.11 in children and 0.23 in parents, a small maternal effect, and a genetic heritability of 0.25 in both generations. Preliminary evidence for a major locus is destroyed by the omission of one exceptional child. There is no evidence

C. L. Gulbrandsen; N. E. Morton; D. C. Rao; G. G. Rhoads; A. Kagan

1979-01-01

485

Proteins and acids from petroleum.  

PubMed

The wax distillate fraction (boiling range 300 up to 400 degrees C) from the crude oil "El-Alameen" was found to be a good substrate for the biosynthesis of proteins and/or amino acids by bacteria under special culture conditions. The fermentation processes were accompanied by a refining effect to the oil fraction, elevating its refraction index and lowering its melting point, giving dewaxing effect to the oil fraction. PMID:735504

Zaki, D; el-Badrawy, S

1978-01-01

486

Catalyzed esterification of oleic acid  

Microsoft Academic Search

Conclusions  It has been shown that the effectiveness of certain divalent metal salts as esterification catalysts can be quantitatively\\u000a compared and that for the Group II B series their effectiveness is inversely proportional to their ionic volume. The rates\\u000a of esterification using these metal salts are not as great as for strong acids, but it is probable that the mechanism is

L. H. Dunlap; J. S. Heckles

1960-01-01

487

Chemical composition of acid fog  

Microsoft Academic Search

Fog water collected at three sites in Los Angeles and Bakersfield, California, was found to have higher acidity and higher concentrations of sulfate, nitrate, and ammonium than previously observed in atmospheric water droplets. The pH of the fog water was in the range of 2.2 to 4.0. the dominant processes controlling the fog water chemistry appear to be the condensation

J. M. Waldman; J. W. Munger; D. J. Jacob; R. C. Flagan; J. J. Morgan; M. R. Hoffmann

1982-01-01

488

Rechargeable lead-acid batteries.  

PubMed

Batteries used in medical equipment, like their counterparts in consumer products, attract little attention until they fail to function effectively. In some applications, such as in emergency medical devices, battery failure can have fatal consequences. While modern batteries are usually quite reliable, ECRI has received 53 written problem reports and countless verbal reports or questions related to battery problems in hospitals during the past five years. This large number of reports is due, at least in part, to the enormous quality of batteries used to operate or provide backup power in contemporary hospital equipment. As part of an ongoing evaluation of rehabilitation assistive equipment, ECRI has been studying the performance of 12 V rechargeable deep-cycle lead-acid batteries used in powered wheelchairs. During the course of this evaluation, it has become apparent that many professionals, both clinical and industrial, regard batteries as "black box" devices and know little about proper care and maintenance--and even less about battery selection and purchase. Because equipment performance and reliability can be strongly influenced by different battery models, an understanding of battery characteristics and how they affect performance is essential when selecting and purchasing batteries. The types of rechargeable batteries used most commonly in hospitals are lead-acid and nickel-cadmium (nicad), which we compare below; however, the guidance we provide in this article focuses on lead-acid batteries. While the examples given are for high-capacity 12 V deep-cycle batteries, similar analyses can be applied to smaller lead-acid batteries of different voltages. PMID:2211174

1990-09-01

489

Chemistry of Phosphoric Acid Phenylesterdiamide  

Microsoft Academic Search

References of methanolytic splitting of the urease inhibitor (1) phosphoric acid phenylesterdiamide (PPDA) at 25°C are given from investigations of time dependent UV absorption behaviour of diluted methanolic PPDA-solutions (2). Exclusion of moisture and addition of solvate free nickel(II)-, cobalt(II)-, manganese(II)-or zinc(II)- acetates or chlorides accelerate solvolytic reactions. Kinetic investigations on this effects indicate catalytic influences in the following sequence

H. Böhland; J. Radicke

1990-01-01

490

Molecular interaction of pinic acid with sulfuric acid: exploring the thermodynamic landscape of cluster growth.  

PubMed

We investigate the molecular interactions between the semivolatile ?-pinene oxidation product pinic acid and sulfuric acid using computational methods. The stepwise Gibbs free energies of formation have been calculated utilizing the M06-2X functional, and the stability of the clusters is evaluated from the corresponding ?G values. The first two additions of sulfuric acid to pinic acid are found to be favorable with ?G values of -9.06 and -10.41 kcal/mol. Addition of a third sulfuric acid molecule is less favorable and leads to a structural rearrangement forming a bridged sulfuric acid-pinic acid cluster. The involvement of more than one pinic acid molecule in a single cluster is observed to lead to the formation of favorable (pinic acid)2(H2SO4) and (pinic acid)2(H2SO4)2 clusters. The identified most favorable growth paths starting from a single pinic acid molecule lead to closed structures without the further possibility for attachment of either sulfuric